Hiv-1 neutralizing antibodies and uses thereof

ABSTRACT

The invention is directed to HIV-1 neutralizing antibodies and methods for their uses.

This application is a continuation application of U.S. application Ser. No. 15/559,314 filed on Sep. 18, 2017, which is a U.S. National Stage application under 35 U.S.C. § 371 of International Patent Application No. PCT/US16/23488, filed Mar. 21, 2016, which application claims the benefit of and priority to U.S. Application Ser. No. 62/135,309 filed Mar. 19, 2015, U.S. Application Ser. No. 62/222,057 filed Sep. 22, 2015, and U.S. Application Ser. No. 62/260,100 filed Nov. 25, 2015, U.S. Application Ser. No. 62/191,095 filed Jul. 10, 2015, U.S. Application Ser. No. 62/191,054 filed Jul. 10, 2015 and U.S. Application Ser. No. 62/261,233 filed Nov. 30, 2015 the content of each application is hereby incorporated by reference in its entirety.

This patent disclosure contains material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure as it appears in the U.S. Patent and Trademark Office patent file or records, but otherwise reserves any and all copyright rights.

All patents, patent applications and publications cited herein are hereby incorporated by reference in their entirety. The disclosure of these publications in their entireties are hereby incorporated by reference into this application in order to more fully describe the state of the art as known to those skilled therein as of the date of the invention described herein.

GOVERNMENT SUPPORT

This invention was made with government support under Center for HIV/AIDS Vaccine Immunology-Immunogen Design grant UM1-A1100645 from the NIH, NIAID, Division of AIDS. The government has certain rights in the invention.

SEQUENCE LISTING

The instant application contains a Sequence Listing which has been filed electronically in ASCII format and is hereby incorporated by reference in its entirety. Said ASCII copy, created on May 5, 2020, is named 1234300_00338US2_SL.txt and is 343,838 bytes in size.

FIELD OF THE INVENTION

The invention relates to the identification of monoclonal HIV-1 neutralizing antibodies, such as, but not limited to, antibodies that bind to the membrane-proximal region of HIV-1 gp41, their recombinant expression and purification and uses.

BACKGROUND

A number of neutralizing monoclonal antibodies (mAbs) have been isolated from HIV-1 infected individuals and these mAbs define specific regions (epitopes) on the virus that are vulnerable to NAbs.

Broadly neutralizing antibodies have been isolated only from natural HIV infection. See e.g. Mascola and Haynes, Immunological Reviews (2013) Vol. 254: 225-244. Some examples of broadly neutralizing antibodies (bnAbs) that bind gp41 at gp41bnAb sites within the membrane proximal region are 2F5, 4E10 and 10E8. These gp41 neutralizing antibodies recognize the membrane-proximal region (MPER) of the HIV-1 gp41 glycoprotein. The advantage of gp41 bnAbs is that they are generally quite broad in their neutralization coverage yet the antibodies to date, have not been developed for prevention or treatment. This is because 2F5 and 4E10 are quite polyreactive and autoreactive, and while mAb 10E8 is less polyreactive, it is autoreactive and is not stable (Haynes B F et al. Science 308: 1906-8, 2005; Yang G, et al. JEM 210: 241-56, 2013; Huang J et al nature 491: 406-412, 2012). Unfortunately, so far none of these antibodies have been developed for HIV prevention or treatment. Thus, the need exists for monoclonal broadly neutralizing antibodies that can be developed and used for prevention and treatment for an infectious agent, such as HIV.

SUMMARY OF THE INVENTION

In certain aspects the invention provides an antibody or fragment thereof with the binding specificity of an MPER antibody as described herein. In non-limiting embodiments the MPER antibody from FIG. 13, FIG. 55, FIG. 56 or FIGS. 30-33 (antibodies with mutations in the DH512 or DH511 VH chain). In non-limiting embodiments, combination mutations in the DH512 or DH511 VHCDR3 could include VH_L100dF together with T100aW FIGS. 31 and 32); VH_L100dW together with T100aW (FIGS. 31 and 32).

Non-limiting examples include antibodies comprising VH or VL chains from DH511, DH512, DH512_K3, DH512-L100dF, DH513, DH514, DH515, DH516, DH517, DH518, lineage members.

In certain embodiments, the antibody or fragment thereof is fully human and recombinantly produced. In certain embodiments, some of the VH and/VL chains are isolated from human subject who have been naturally infected with HIV. In certain embodiments the antibody is not naturally occurring. In certain embodiments the antibody comprises naturally occurring pair of VH and VL chains. In certain embodiments the antibody comprises naturally occurring pair of VH and VL chains wherein the Fc portion of the antibody is not the natural isotype or portion of the naturally occurring pair of VH and VL chains. In certain embodiments the antibody is computationally designed, for example based on some naturally isolated VH and VL sequences. In certain embodiments the antibody is computationally designed, e.g., UCA, Intermediates in the antibody lineages. In certain embodiments the antibody comprises a non-naturally occurring pairing of VH and VL chains, wherein the VH or VL individually could be isolated from a subject. In some embodiments, the antibody comprises VH chain or HCDRs of a VH chain of one clonal member, and VL or LCDRs of another clonal member, i.e., a non-naturally occurring antibody comprising sequences derived from natural pairs.

In certain embodiments, the antibody or fragment thereof comprises a VH chain that is 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the VH chain of antibody DH511, DH512, DH513, DH514, DH515, DH516, DH517, DH518, DH536, DH537, DH491 or DH493, or an antibody from Example 10, 11 or 12.

In certain embodiments, the antibody or fragment thereof comprises a VL chain that is 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the VL chain of antibody DH511, DH512, DH513, DH514, DH515, DH516, DH517, DH518, DH536, DH537, DH491 or DH493, or an antibody from Example 10, 11 or 12.

In certain embodiments, the antibody or fragment thereof comprises a VH chain that is 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the VH chain of antibody DH511, DH512, DH513, DH514, DH515, DH516, DH517, DH518, DH536, DH537, DH491 or DH493 and further comprises a VL chain that is 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% identical to the VL chain of antibody DH511, DH512, DH513, DH514, DH515, DH516, DH517, DH518, DH536, DH537, DH491 or DH493, or an antibody from Example 10, 11 or 12.

In certain embodiments, the antibody or fragment thereof comprises a VH which comprises the HCDR1, HCDR2, and HCDR3 of antibody DH511, DH512, DH513, DH514, DH515, DH516, DH517, DH518, DH536, DH537, DH491 or DH493, or an antibody from Example 10, 11 or 12.

In certain embodiments, the antibody or fragment thereof comprises a VL which comprises the LCDR1, LCDR2, and LCDR3 of antibody DH511, DH512, DH513, DH514, DH515, DH516, DH517, DH518, DH536, DH537, DH491 or DH493, or an antibody from Example 10, 11 or 12.

In certain embodiments, the antibody or fragment thereof comprises a VH which comprises the HCDR1, HCDR2, and HCDR3 of antibody DH511, DH512, DH513, DH514, DH515, DH516, DH517, DH518, DH536, DH537, DH491 or DH493, or an antibody from Example 10, 11 or 12 and further comprises the complementary VL which comprises the LCDR1, LCDR2, LCDR3 of antibody DH511, DH512, DH513, DH514, DH515, DH516, DH517, DH518, DH536, DH537, DH491 or DH493, or an antibody from Example 10, 11 or 12.

In certain embodiments, the antibody or fragment thereof comprises VH and VL of antibody DH511, DH512, DH513, DH514, DH515, DH516, DH517, DH518, DH536, DH537, DH491 or DH493, or an antibody from Example 10, 11 or 12.

In certain embodiments, the antibody is DH511, DH512, DH513, DH514, DH515, DH516, DH517, DH518, DH536, DH537, DH491 or DH493, or an antibody from Example 10, 11 or 12, e.g. without limitation DH511_5a_ or DH511_5b, DH512_K3.

In certain aspects, the invention provides a pharmaceutical composition comprising anyone of the antibodies of the invention or fragments thereof or any combination thereof.

In certain aspects, the invention provides a pharmaceutical composition comprising anyone of the antibodies of the invention, or a combination thereof.

In certain embodiments, the composition comprises an antibody or a fragment thereof which is recombinantly produced in CHO cells.

In certain aspects, the invention provides a pharmaceutical composition comprising a vector comprising a nucleic acid encoding anyone of inventive antibodies or fragments. In certain embodiments, the nucleic acids are optimized for expression in human host cells. In certain embodiments, the vector is suitable for gene delivery and expression. Non-limiting examples of such vectors include adenoviral vectors (Ads), adeno associated virus based vectors (AAVs), or a combination thereof.

In certain embodiments, the compositions further comprise an antibody or a fragment thereof comprising the VH and VL chains of antibody DH540.

In certain embodiments, the compositions further comprise an antibody or a fragment thereof comprising VH and VL chain of antibody CH557 or DH270 lineage antibody, for example without limitation DH542, DH542-QSA, DH542_L4.

In certain aspects the invention provides a bispecific antibody which comprises gp41 MPER binding specificity. In some embodiments the MPER binding portion of the bispecific antibody comprises VH and/or VL chains, variants or fragments thereof.

In certain aspects the invention provides methods to treat or prevent HIV-1 infection in a subject comprising administering to the subject the pharmaceutical composition of any one of the preceding claims in a therapeutically effective amount.

In certain embodiments of the methods, the pharmaceutical composition is administered in a therapeutically effective regimen.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows Neutralization-based Epitope Prediction (NEP) Analysis. Neutralization-based epitope prediction analysis. The predicted relevant prevalence of antibody clusters [(10 epitopes targeting sites of vulnerability (CD4 binding site, V1/V2, MPER, glycan V3)] is shown as a heat map, with dark color intensity (higher fractional number) corresponding to a stronger neutralization signal. Plasma neutralization breadth is shown, and numbers in each row add up to 1.00. NEP algorithm reference: [Georgiev I S et al Science 340: 751-756].

FIG. 2 shows MPR.03 Hook sequence (SEQ ID NOs: 1-2). MPR.03 is a biotinylated peptide containing lysines at both ends for solubility (KKKNEQELLELDKWASLWNWFDITNWLWYIRKKK-biotin) (SEQ ID NO: 463) used to pull out gp41 antibodies from blood memory B cell sorts See Morris L. et al. (2011) PLoS ONE 6(9): e23532.

FIG. 3 shows a representative CH0210 mper03 sort (sort #1).

FIG. 4 shows V(D)J Rearrangement of MPER Antibodies Isolated from Four HIV-1 Infected Individuals. * indicates that these mAbs neutralized the tier 1 isolate MN in TZM-bl cells. Mutation refers to VH nucleotide sequence somatic mutation percentages in the variable heavy (VH) immunoglobulin (Ig) genes.

FIG. 5 shows Neutralization Titers of MPER Antibodies Isolated from Four HIV-1 Infected Individuals using a small panel of HIV-1 isolates in the TZMbl pseudovirus inhibition assay.

FIG. 6 shows the MPER BnAb DH511 VH Phylogram of the B Cell Clonal Lineage Derived from Subject 0210. Antibodies in clone DH511 include the following: DH511, DH512, DH513, DH514, DH515, DH516 and DH520.

FIG. 7 shows summary results of neutralization of gp41 antibodies against a panel of 30 HIV-1 tier 2 isolates in the TZMbl pseudovirus neutralization assay. Data show that antibodies in the DH511 B cell clonal lineage (DH511-DH516) all neutralize 100% of 30 HIV-1 isolates tested in the TZMbl Env pseudovirus neutralization assay.

FIG. 8 shows Neutralizing Breadth and Potency of DH512, DH517 and DH518 HIV-1 BnAbs compared to 10E8, VRC01 and a mixture of CH01 and CH31 bnAbs. DH512 neutralizes 100% of HIV strains and is as at least as potent as 10E8.

FIG. 9 shows Neutralizing Breadth and Potency of various HIV-1 BnAbs that are candidates for being combined with DH512 or other antibodies in FIG. 4 for a potent mixture of bnAbs. DH270IA1 is I1 in the DH270 lineage (See FIG. 26, and U.S. Ser. No. 62/056,568 filed Sep. 28, 2014)

FIG. 10 shows Neutralizing Breadth and Potency of some candidate bnAbs for single or combination use.

FIG. 11 shows summary of Clone DH511 binding to the indicated peptides (SEQ ID NOs: 3-14) in ELISA. Clone DH511 antibodies bind at the C-terminus of the MPER. “+” indicates that antibodies in the Clone DH511 bind to the peptide. The summary shows that DH511 clone antibodies do not bind the peptides when D674 is mutated to 5674. The twelve sequences of the peptides (without the three lysines at the N— and C— end) are shown in SEQ ID NOs: _ to _. The twelve sequences of the peptides (with the three lysines at the N— and C— end) are shown in SEQ ID NOs: 3 to 14. Thus, antibody DH511 requires an aspartic acid at amino acid position 674 for binding.

FIG. 12 shows nucleic acid sequences of antibodies DH511-518, DH536 and 537 (SEQ ID Nos: 15 to 34).

FIG. 13 shows amino acid sequences of antibodies DH511-518, DH536 and 537. (SEQ ID Nos: 35 to 55)

FIGS. 14A-B show Alignment of VH (FIG. 14A; (SEQ ID Nos: 56-61)) and VL (FIG. 14B (SEQ ID Nos: 62-67)) Sequences of BnAb DH511 Clonal Lineage. Bolded is the sequence of CDR1, underlined is the sequence of CDR2 and italicized is the sequence of CDR3 of the DH511 VH chain and DH511 VL chain. The CDRs of the VH and VL sequences of the other antibodies DH512, DH513, DH514, DH515, and DH516 can be readily determined based on the sequence alignment.

FIGS. 15A-B show Alignment of VH (FIG. 15A (SEQ ID Nos: 68-76)) and VL (FIG. 15B (SEQ ID Nos: 77-85)) sequences of MPER BnAbs. Bolded is the sequence of CDR1, italicized is the sequence of CDR2 and underlined is the sequence of CDR3 of VH or VL of the listed MPER antibodies.

FIG. 16 shows sequences of MPER alanine mutants (SEQ ID NOs: 86-112) screened in ELISA. All antibodies in the DH51 clone showed weak binding to this peptide set. DH517 (Ab510053) strongly bound to MPER656 peptide and showed decreased binding to several residues (A4, A6-A13, A16-A18, A20, A23, A24, A26) using the ala substituted peptides in table.

FIG. 17 shows Binding of DH517 (Ab510053) to alanine substituted MPER-26 peptides. The binding studies do not conclusively map the DH517 epitope.

FIG. 18 shows MPER656 variants (SEQ ID NOs: 113-124) screened in ELISA. Residues shown in light blue (underlined) indicate positions that differ from MPER656-biotin.

FIG. 19 shows Binding of DH511 (Ab510056) to MPER656 variants

FIG. 20 shows Binding of DH512 (Ab510049) to MPER656 variants

FIG. 21 shows Binding of DH513 (Ab570022) to MPER656 variants

FIG. 22 shows Binding of DH514 (Ab570029) to MPER656 variants

FIG. 23 shows Binding of DH515 (Ab510052) to MPER656 variants

FIG. 24 shows Binding of DH516 (Ab510048) to MPER656 variants

FIG. 25 shows Binding of DH518 (Ab570010) to MPER656 variants.

FIG. 26 shows the amino acids sequences of VH (SEQ ID NOs: 137-148) and VL (SEQ ID NOs: 161-172) chains of antibodies of the DH270 lineage, and nucleic acid sequences (SEQ ID NOs: 125-136 (VH); SEQ ID NOs: 149-160 (VL)) encoding these amino acids. CDRs are highlighted and underlined in the UCA.

FIG. 27A shows amino acid (SEQ ID Nos: 173 and 174) and nucleic acid sequences (SEQ ID Nos: 175 and 176) of CD4bs antibody CH557. FIG. 27B shows amino acid sequences of VH chains of antibodies from CH235 lineage (SEQ ID NOs:177-188). FIG. 27C shows amino acid sequences of VL chains of antibodies from CH235 lineage (SEQ ID NOs: 189-198).

FIG. 28A shows neutralization Breadth and Potency of Plasma and Memory B cell (MBC)-derived MPER bnAbs. FIG. 28B shows neutralization Breadth and Potency of chimeric MPER bnAbs (n=30 cross-clade HIV-1 isolates)

FIGS. 29A and B show neutralization data from TZM-bl assay (Titer in TZM.bl cells (ug/ml) for DH512_K3 and other chimeric antibodies compared to DH512 and 10E8. The data in the first column is historic data when DH512 was run in this panel previously. DH512 was run at the same time as DH512_K3 but is listed as Ab510049 in this assay; therefore, data from columns DH512_K3 and AA&AB DH512/Ab510049 should be compared.

FIG. 30 shows positions in the VHCDR3 chain of DH511 (SEQ ID NO: 471) which could be mutated. Amino acid positions refer to Kabat numbering. Most mutations are to changes to W, but F, L or possibly other substitutions can be tried.

FIG. 31 shows positions in the VHCDR3 chain of DH512 (SEQ ID NO: 472) which could be mutated. Amino acid positions refer to Kabat numbering for the DH512VH chain: QVQLVQSGGGLVKPGGSLTLSCSASGFFFDNSWMGWVRQAPGKGLEWVGRIRRLK DGATGEYGAAVKDRFTISRDDSRNMLYLHMRTLKTEDSGTYYCTMDEGTPVTRFLE WGYFYYYMAVWGRGTTVIVSS (SEQ ID NO: 469). Most mutations are to changes to W, but F, L or possibly other substitutions can also be tried. Position V100 can be changed to I. Position L100d can be changed to F.

FIG. 32 shows positions outside of VHCDR3 which could be mutated (SEQ ID NOs: 473-478, respectively, in order of appearance). Most mutations are to changes to W, but F, L or possibly other substitutions can also be tried.

FIG. 33 shows amino acid sequences (SEQ ID NOs: 199-216) of some of the DH512 mutants from FIG. 31.

FIG. 34 shows neutralization data for a set of 16 mutations from FIG. 31. In this figure DH512 is referred to as DH512 (Ab510049_4A): its heavy chain is H510049_4 and its light chain is K510032

FIG. 35 shows summary of anti-cardiolipin activity of various antibodies as measured by QUANTA Lite® ACA IgG III kit. Data plotted are representative of 2 independent experiments. mAb were run in duplicate in the second assay. Mean error and standard deviation are shown. Data were consistent between assays. Dotted line indicates positivity cut-off of 0.18. mAbs with OD values above 0.18 are bolded in the figure legend (DH514, DH518-315 HC, DH511-I6-4a through DH511_I1_4A; 4E10).

FIG. 36 shows a summary of self-reactivity data of MPER antibodies.

FIG. 37 shows summary results of neutralization data of DH512 and 10E8 against a panel of HIV-1 isolates in the TZMbl pseudovirus neutralization assay. Values represent IC50 in μg/ml. FIG. 37 also shows the mean IC50 and percent of isolates neutralized at different IC50 values.

FIG. 38 shows summary results of neutralization data of DH512 and 10E8 against a panel of HIV-1 isolates in the TZMbl pseudovirus neutralization assay. Values represent IC80 in μg/ml. FIG. 38 also shows the mean IC80 and percent of isolates neutralized at different IC80 values.

FIG. 39 shows Experimental Overview of Paired VH-VL Sequencing and antibody identification (Example 10). V gene repertoire sequencing. Identification of individual monoclonal antibodies requires the generation of a sample-specific database of IgG VH sequences constructed by next-generation sequencing of mature B cells isolated from the PBMCs of the donor. Reads are processed bioinformatically to obtain a database of unique VH sequences, which then are clustered into clonotypes according to their CDR3 sequences. The obtained database is used to interpret the MS spectra. F(ab)2 purification and proteomic analysis. F(ab)2 fragments are prepared from total serum IgG and subjected to antigen-affinity chromatography (monomeric gp120). Proteins in the elution and flow-through are denatured and reduced, alkylated, trypsin-digested and analyzed by high resolution LC-MS/MS. Spectra are interpreted with the sample-specific VH database and peptides uniquely associated with a single CDR3 are used to identify full-length VH sequences.

FIG. 40 shows MPER BnAb DH511 Clonal Lineage Derived from African Individual CH0210 (the heavy chain for DH511_1A is not included).

FIG. 41 shows Neutralization Activity (IC50) of MPER Antibodies Identified by Paired VH:VL Sequencing Technology (Example 10). Summary data of two independent assays.

FIG. 42 shows Neutralization Activity (IC80) of MPER Antibodies Identified by Paired VH:VL Sequencing Technology (Example 10). Summary data of two independent assays.

FIG. 43 shows Nucleotide Alignment of MPER Antibody Heavy Chain Sequences (SEQ ID NOs: 217-229).

FIG. 44 shows Amino Acid Alignment of MPER Antibody Heavy Chain Sequences (SEQ ID NOs: 230-242).

FIG. 45 shows Nucleotide Alignment of MPER Antibody Light Chain Sequences (SEQ ID NOs: 243-252).

FIG. 46 shows Amino Acid Alignment of MPER Antibody Light Chain Sequences (SEQ ID NOs: 253-262).

FIG. 47 shows Immunogenetic Characteristics of MPER Antibodies—Original Pairings.

FIG. 48 shows epitope mapping of antibodies of Example 10. Binding to various MPER peptides in an ELISA assay was used to map the epitopes of these MPER antibodies.

FIG. 49 show epitope mapping of antibodies of Example 10. Binding to various MPER peptides in an ELISA assay was used to map the epitopes of these MPER antibodies.

FIG. 50 show epitope mapping of antibodies of Example 10. Binding to various MPER peptides in an ELISA assay was used to map the epitopes of these MPER antibodies.

FIG. 51 show epitope mapping of antibodies of Example 10. Binding to various MPER peptides in an ELISA assay was used to map the epitopes of these MPER antibodies.

FIG. 52 show epitope mapping of antibodies of Example 10. Binding to various MPER peptides in an ELISA assay was used to map the epitopes of these MPER antibodies.

FIG. 53 shows Poly/Autoreactivity analysis of DH511_5a. Antibody DH511_5a appears to be autoreactive with one protein (NUDC).

FIG. 54 shows Poly/Autoreactivity analysis of DH511_5b. Antibody DH511_5b appears to be polyreactive.

FIG. 55 shows Antibody Pairings—Heavy and Light Chain Chimeric Antibodies from Example 11.

FIG. 56A shows neutralization activity of Heavy and Light Chain Chimeric Antibodies chimeric pairings 1-32 (from FIG. 55). FIG. 56B shows Neutralization Activity on New Pairings in rows 33-67 (from FIG. 55). FIG. 56C shows Neutralization Activity on New Pairings in rows 68-91 (from FIG. 55). FIG. 56D shows that 8 chimeric antibodies were selected for large scale expression and neutralization activity analysis.

FIG. 57 shows nucleic acid and amino acid sequences of VH and VL sequences of antibodies from Example 10 (SEQ ID NOs: 263-300).

FIG. 58 shows sequences of DH511_5a and 5b as Fabs (SEQ ID NOs: 301-304).

FIGS. 59A-F show isolation of MPER-directed broadly neutralizing antibodies. (a) Fluorescently-labeled MPR.03 peptide tetramers were used to stain peripheral blood mononuclear cells from donor CH0210. A representative flow cytometric plot is shown. Square represents frequency of MPR.03 double positive memory B cells that were single-cell sorted for Ig gene amplification and expression. Colored dots within the square show individual cells that yielded MPER-specific monoclonal antibodies DH511.1-DH511.6 as revealed by index sorting. Memory B cells were gated as live CD16-CD14-CD3-CD235-CD19+IgD-CD38hi. (b) Phylogenetic tree of VHDHJH sequences of the DH511 clonal lineage. Ancestral reconstruction of the evolutionary pathway from the inferred unmutated common ancestor (UCA) to the mature mAbs including 6 maturational intermediates (circles, 11-16) is indicated. (c) Neutralization activity of probe-identified MPER antibodies against a panel of 199 cross-clade HIV-1 isolates. Median and geometric mean neutralization potency against viruses neutralized with a median IC50/IC80<50 μg/ml is indicated. Percentage of 199 viruses neutralized by mAbs DH511.1-DH511.6, 10E8, and VRC01 at IC50<50 μg/ml, IC50<1 μg/ml, and IC50<0.1 μg/ml. (d) Neutralization potency and breadth of DH511.2 compared to 10E8 and VRC01 against a 199 HIV-1 Env pseudovirus panel displayed as potency-breadth curves. Percentage of isolates neutralized at IC50 (top panel) and IC80 (bottom panel) values is plotted against mAb concentration. (e) Percent maximum neutralization of each isolate by DH511.2 is shown. (0 Identification of MPER-directed broadly neutralizing plasma antibodies by proteomics. Phylogenetic tree of heavy chain sequences identified in the plasma (black) and in the memory B cell compartment (grey, see FIG. 59b ). The bar on the right shows the relative abundance of the three identified clonotypes in serum (IV: 95%, II: 4%, III: 1%).

FIGS. 60A-E shows structural analysis of the DH511 lineage. (a) Ribbon model of crystal structures of DH511.1 and DH511.2 Fabs in complex with gp41 MPER peptides 656-683 and 662-683, respectively, oriented based on Ca-atom superposition of distal MPER residues 671-683. (b) Close-up view of antibody-peptide contacts. gp41 residues that interact with antibody VH3-15 region residues, HCDR3 residues, or both, are shown in cyan, red, and brown, respectively. (c) Ribbon model of crystal structures of Fabs of plasma-derived variants DH511.11P and DH511.12P are shown in complex with gp41 MPER peptide 662-683 [511.11P is placeholder here]. Residues shown in surface representation differ in sequence from DH511.1 or DH511.2. Of the residues that are unique to DH511.11P and DH511.12P, those at the interface with gp41 are colored red and are predominantly located within their HCDR3 loops. (d) Close-up view of DH511.11P and DH511.12P antibody-peptide contacts, with gp41 contacting residues colored as in b. (e) Sequence alignment of DH511 lineage antibodies (SEQ ID NOs: 305-310), antibody 10E8, and their shared VH3-15 germ line gene precursor. Residues that contact gp41 are labeled with closed circles, and somatically-mutated residues shaded red, orange blue, and green, for 10E8, DH511.1, DH511.2, and DH511.11P and DH511.12P, respectively.

FIGS. 61A-E shows comparison with other MPER-specific antibodies. (a) Crystal structures of DH511.1 and DH511.2 Fab in complex with gp41 MPER peptides 656-683 and 662-683, respectively, oriented based on Ca-atom superposition of distal MPER residues 671-683. (b) Crystal structures of antibodies 10E8 and 4E10 in complex with MPER peptide epitopes, oriented as in (a). (c) Surface representations of antibodies DH511.1, DH511.2, and 10E8, colored as in (a) and (b) and rotated by 60°. gp41 contact footprints within the HCDR3 loops are colored red and those within the variable heavy chain VH3-15 regions are colored green. VH3-15 contacting residues positions that are shared by antibodies DH511.1 and DH511.2 and antibody 10E8 are colored cyan. (d) Angles of approach to distal gp41 MPER by antibodies DH511.1, DH511.2, 10E8, and 4E10. Shown is a superposition of the structures of antibody-bound gp41 MPER, with lines representing the longitudinal and latitudinal axes of antibody variable regions colored as in (a) and (b). The longitudinal axis is drawn to the Ca atom of gp41 residue 672 from the center of the latitudinal axis, defined as the point midway between heavy and light chain intra-chain disulfide bonds (spheres).

FIGS. 62A-C show standard experimental mapping and neutralization-based epitope prediction analysis to delineate the specificities that mediate plasma neutralization breadth. (a) Plasma from donor CH0210 showed potent MPER-directed neutralizing activity against the HIV-2/HIV-1 MPER chimeric pseudovirus C1C. Neutralization titer is reported as median inhibitory dilution (ID50). (b) Neutralization activity adsorbed with MPER peptide. Anti-MPER antibodies were depleted from plasma using MPER peptide-coated magnetic beads. The depleted fraction was tested for neutralization activity against the indicated heterologous viruses. Neutralization was considerably diminished by removal of anti-MPER from both plasmas, indicating that MPER antibodies were largely responsible for neutralization breadth. ND, not determined. (c) Neutralization-based epitope prediction (NEP) analysis. The predicted relative prevalence of antibody clusters [(10 epitopes targeting sites of vulnerability (CD4 binding site, V1/V2, MPER, glycan V3)] is shown as a heat map, with dark color intensity (higher fractional number) corresponding to a stronger neutralization signal. Plasma neutralization breadth is shown, and numbers in each row add up to 1.00. Shown below are the locations on the Env trimer of the epitopes identified by NEP for this donor and confirmed to be targeted by standard experimental mapping methods.

FIGS. 63A-B show frequency and identity of CDR3 peptides from MPER affinity chromatography. (a) Representative histogram of antibody clonotype frequencies identified proteomically in the F(ab)′2 elution and flow through fractions following MPER affinity purification. Clonotypes were defined as genes with the same V- and J-gene usage and >85% sequence identity in the HCDR3. Frequencies of the identified clonotypes were based on the average peak areas of the detected CDR peptides. (b) Identified clonotypes and gene usage (SEQ ID NOs: 311-320).

FIG. 64 shows Phylogenetic tree of VHDHJH sequences of memory B cell and plasma-derived DH511 clonal lineage members.

FIGS. 65A and 65B show Epitope mapping by alanine scanning mutagenesis of C-terminal MPER residues. Values listed are mean measurements from two independent experiments. Epitope residues were defined as residues where log AUC relative to wild-type (WT) for alanine mutations was reduced by 50%.

FIG. 66A-C show Surface-plasmon resonance analysis of binding of the DH511 clonal lineage to MPR.03 peptide. FIG. 66C shows Association (ka) and dissociation (kd) rate constants and binding affinities (Kd) for each Fab.

FIG. 67A-C show Surface-plasmon resonance analysis of binding of the DH511 clonal lineage to MPER liposomes (SEQ ID NOs: 321-325).

FIG. 68A-C show poly/autoreactivity analysis of MPER bNAbs. Reactivity of DH511 clonal lineage members with self-antigens as measured by indirect immunofluorescence Hep-2 cell staining (b) and a multiplex bead array anti-nuclear antibody (ANA) assay (a) panel consisting of several autoantigens: SSA, SSB, Smith antigen (Sm), ribonucleoprotein (RNP), Scl-70, Jo-1, double-stranded DNA (dsDNA), Cent B, Histone, and anti-cardiolipin. None of the antibodies were identified as reactive with Hep-2 cells. DH511.1 UCA reacted with ribonucleoprotein, and DH511 I6 reacted with dsDNA. (c) Protein microarrays were used to assess binding to >9400 human proteins. Autoantigens identified: PPP1R1C (protein phosphatase 1, regulatory (inhibitor) subunit 1C) [DH511.1]; FYN (FYN oncogene related to SRC, FGR, YES, transcription variant 1 [DH511.1, DH511.3, DH511.6, DH511_I3, DH511_I4]; NECAP endocytosis associated 1 (NECAP1) [DH511.1, DH11.6]; SIAHBP1 (fuse-binding protein-interacting repressor, transcription variant 1, mRNA) [DH511.11]; STUB 1 (STIP1 homology and U-box containing protein 1) [DH511.2, DH511.6] STIP1 (stress-induced phosphoprotein 1) [DH511 DH511_I2]; OR1F1 (olfactory receptor, family 1, subfamily F, member 1) [DH511]; C6orf145 (Px-domain containing protein) [DH511.1]; FLJ36032 [DH511_UCA]; TTC1 (tetratricopeptide repeat domain 1) [DH511_I1], nuclear distribution gene C homolog (A. nidulans) (NUDC) [DH511.11P, DH511.12P], Scm-like with four MBT domains protein 1 [DH511.12P].

FIG. 69 shows ELISA binding of DH511 lineage members to U1 snRNP components. The DH511_UCA bound specifically to U1-snRNPA while no binding was observed to the other components. Results shown represent one experiment.

FIG. 70 shows potential mechanistic differences in binding of 4E10 versus DH511.2/10E8 to MPER liposomes. 4E10 bound to MPER656.1 in a biphasic association/dissociation mode and the binding could be fit to a 2-step conformational change model. DH512 appears to have a different mechanistic mode and its binding could be fit to a 1:1 Langmuir model.

FIG. 71A-C show DH511.2 recognizes a transiently exposed intermediate state of gp41, and the lifetime of DH511.2 epitope exposure is the same as that of 10E8 and 4E10. Time course of neutralization of tier 2 HIV-1 isolate B.BG1168 was measured by addition of mAbs to TZM-bl cells pre-incubated with virus. Half-life values were similar among the three antibodies.

FIG. 72 shows Sequence Comparison of DH511, DH512, and 10E8 HCDR3 Loops (SEQ ID NOs: 326-328). The figure shows that while HCDR3 loops of DH511 and 10E8 lineages are both encoded by D3-3 precursor, substantial differences are observed in their final matured lengths and sequences. One conserved sequence motif between DH511/DH512 and 10E8 HCDR3s appears to be a hydrophobic residue doublet at the center of the loop (boxed).

FIG. 73A-D shows Structural Comparison of DH511 (A), DH512 (B), and 10E8 (C)HCDR3 Loops. Conserved DH511/DH512 and 10E8 hydrophobic residue doublets at apex of HCDR3 loops are spatially co-localized (D), relative to MPER. Comparison is based on Ca superposition of MPER residues 671-683.

FIGS. 74A-B shows Comparison of DH511, DH512, and 10E8 HCDR3 Loops. (a) Sequence alignment of HCDR3 loops of DH511, DH512, and 10E8 (SEQ ID NOs: 329-331). (b) Structural comparison of HCDR3 loops based on alignment of distal MPER gp41 residues (that CDRH3 orientation differs from FIG. 73). The HCDR3 loops of bNabs that target the gp41 MPER have been shown to be critical for their capacity to neutralize the HIV-1 virus, largely through interactions with the viral membrane. Mutations that reduce hydrophobicity of the HCDR3 loops ablate virus neutralization, while mutations that augment hydrophobicity in turn augment neutralization potency. Given that the DH511 lineage shares a common D3-3 gene with 10E8, we sought to compare the sequences and structures of their respective HCDR3 loops to assess whether common characteristics could be discerned. While sequence alignment of their matured amino acid sequences were quite different, as were their lengths, a conserved hydrophobic residue doublet at the centers of both loops was observed. These two residues have previously been shown to be critical for 10E8 epitope binding and neutralization. Remarkably, despite the overall differences in sequence and length of the DH511/12 and 10E8 HCDR3 loops, when they were compared structurally based on an alignment of MPER distal residues, the conserved hydrophobic residue doublets at their tips ended up spatially co-localized relative to MPER. Studies are underway to assess the importance of these two residues in the DH511 context, and the structures are being utilized to introduce additional mutations that are aimed at improving the neutralization potency of DH511-lineage antibodies as immunotherapeutics. 1Huang, J. et al. Broad and potent neutralization of HIV-1 by a gp41-specific human antibody. Nature 491, 406-412, doi:10.1038/nature11544 (2012).

FIG. 75 shows sequence characteristics of MPER antibodies isolated from memory B cells (SEQ ID NOs: 332-359). FIG. 75 corresponds to Supplementary Table 1 as referenced in Example 12.

FIG. 76 shows neutralization activity of MPER mAbs against a cross-clade 30 isolate HIV-1 Env-pseudovirus panel (IC50 values). FIG. 76 corresponds to Supplementary Table 2a as referenced in Example 12.

FIG. 77 shows neutralization activity of MPER mAbs against a cross-clade 30 isolate HIV-1 Env-pseudovirus panel (IC80 values). FIG. 77 corresponds to Supplementary Table 2b as referenced in Example 12.

FIG. 78 shows neutralization activity of DH511.2 against a cross-clade 199 isolate HIV-1 Env-pseudovirus panel. FIG. 78 corresponds to Supplementary Table 3 as referenced in Example 12.

FIG. 79 shows neutralization activity of DH511.2 against a panel of 200 clade C HIV-1 primary isolates. FIG. 79 corresponds to Supplementary Table 4 as referenced in Example 12.

FIG. 80 shows neutralization activity of 16 DH511.2 heavy chain mutant antibodies. FIG. 80 corresponds to Supplementary Table 27 as referenced in Example 12.

FIG. 81 shows sequence characteristics and pairing of plasma-derived heavy and light chains identified by mass spectrometry and paired VH-VL next-generation sequencing (SEQ ID NOs: 360-367 and 479-489, respectively, in order of appearance). FIG. 81 corresponds to Supplementary Table 6 as referenced in Example 12.

FIG. 82 shows neutralization activity of 16 plasma mAbs against a 4 indicator HIV-1 Env pseudovirus panel. FIG. 82 corresponds to Supplementary Table 7 as referenced in Example 12.

FIG. 83 shows neutralization activity of plasma mAbs DH511.11P and DH511.12P against a cross-clade 203 isolate HIV-1 Env-pseudovirus panel. FIG. 83 corresponds to Supplementary Table 8 as referenced in Example 12.

FIG. 84 shows sequences of alanine substituted MPR.03 peptides (SEQ ID NOs: 368-381). FIG. 84 corresponds to Supplementary Table 9 as referenced in Example 12.

FIG. 85 shows sequences of COT6.15 MPER mutant viruses (SEQ ID NOs: 382-403). FIG. 85 corresponds to Supplementary Table 10 as referenced in Example 12.

FIG. 86 shows neutralization Activity Against a series of MPER alanine mutant pseudoviruses in the COT6.15 Env background. FIG. 86 corresponds to Supplementary Table 11 as referenced in Example 12.

FIG. 87 shows crystallization peptides (SEQ ID NOs: 404-406). FIG. 87 corresponds to Supplementary Table 12 as referenced in Example 12.

FIG. 88 shows crystallographic data collection and refinement statistics. FIG. 88 corresponds to Supplementary Table 13 as referenced in Example 12.

FIG. 89 shows antibody contact interfaces by CDR loop. FIG. 89 corresponds to Supplementary Table 14 as referenced in Example 12.

FIG. 90 shows bonded and non-bonded contacts DH511.1-MPER. (Non-Kabat numbering). FIG. 90 corresponds to Supplementary Table 15 as referenced in Example 12.

FIG. 91 shows bonded and non-bonded contacts DH511.2-MPER. (Non-Kabat numbering). FIG. 91 corresponds to Supplementary Table 16 as referenced in Example 12.

FIG. 92 shows bonded and non-bonded contacts DH511.11P-MPER. FIG. 92 corresponds to Supplementary Table 17 as referenced in Example 12.

FIG. 93 shows bonded and non-bonded contacts DH511.12P-MPER. (Non-Kabat numbering). FIG. 93 corresponds to Supplementary Table 18 as referenced in Example 12.

FIG. 94 shows neutralization of the DH511 clonal lineage against a panel of 12 global HIV-1 reference strains. FIG. 94 corresponds to Supplementary Table 19 as referenced in Example 12.

FIGS. 95A-C show primers and PCR conditions for paired VH:VL NGS. FIG. 95A shows overlap extension oligonucleotides for framework region 1 (5′-3′) (SEQ ID NOs: 407-427). FIG. 95B shows overlap extension oligonucleotides for leader peptide (5′-3′) (SEQ ID NOs: 428-441). FIG. 95C shows nested constant region oligonucleotides (5′-3′) (SEQ ID NOs: 442-446). FIG. 95A corresponds to Supplementary Table 28 as referenced in Example 12. FIG. 95B corresponds to Supplementary Table 29 as referenced in Example 12. FIG. 95C corresponds to Supplementary Table 30 as referenced in Example 12.

FIG. 96 shows DH511 clonal lineage membrane insertion scores and HCDR3 analysis (SEQ ID NOs: 447-455). The membrane insertion scores can be recalculated to exclude the C in the CDR3. HCDR3s score for the .P antibodies will be calculated. FIG. 96 corresponds to Supplementary Table 21 as referenced in Example 12.

FIG. 97 shows cardiolipin reactivity of the DH511 clonal lineage. FIG. 97 corresponds to Supplementary Table 22 as referenced in Example 12.

FIG. 98 shows neutralization activity of 91 chimeric MPER mAbs against the tier 2 HIV-1 isolate B.BG1168. FIG. 98 corresponds to Supplementary Table 23 as referenced in Example 12.

FIG. 99 shows neutralization activity of chimeric mAb DH511.2_K3 against a cross-clade 30 isolate Env-pseudovirus panel. FIG. 99 corresponds to Supplementary Table 24 as referenced in Example 12.

FIGS. 100A-C show primers and PCR conditions for paired VH:VL NGS. FIG. 100A shows PCR conditions for isotype specific amplification. FIG. 100B shows oligonucleotides for isotype specific amplification (5′-3′) (SEQ ID NOs: 456-462). FIG. 100C shows PCR conditions for MiSeq Barcoding. FIG. 100A corresponds to Supplementary Table 30 as referenced in Example 12. FIG. 100B corresponds to Supplementary Table 31 as referenced in Example 12. FIG. 100C corresponds to Supplementary Table 32 as referenced in Example 12.

DETAILED DESCRIPTION

Broadly neutralizing and potent HIV envelope antibodies are now being developed for both prevention of HIV (Rudicell R S et al. J. Virol 88: 12669-82, 2014) and for treatment of HIV infected individuals (Barouch D H, et al. Nature 503: 224-8, 2013; Shingai M et al. Nature 503: 277-80, 2013). Thus, human recombinant antibodies either alone or in combinations have great prophylactic and therapeutic potential for the prevention and treatment of HIV. Moreover, antibodies that bind with high affinity to Env may be useful in eliminating the latent pool of HIV-infected CD4 T cells and curing HIV, when either used to sensitize HIV expressing target cells with bispecific bnAbs for NK or CD8 T cell killing or when bnAbs are conjugated with toxins or radionucleotides.

In certain aspects the invention provides fully human antibodies and fragments that specifically bind to and potently neutralize various isolates of HIV-1. In some embodiments, the antibodies bind to HIV-1 gp41. In some embodiments, the antibodies of the invention specifically bind the membrane-proximal extracellular region (MPER) of gp41.

In certain aspects the invention provides pharmaceutical compositions including these human antibodies and a pharmaceutically acceptable carrier. In certain aspects the invention provides antibodies for passive immunization against HIV/AIDS. Nucleic acids encoding these antibodies, expression cassettes and vectors including these nucleic acids, and isolated cells that express the nucleic acids which encode the antibodies of the invention are also provided.

In some embodiments, the invention provides antibodies which are clonal variants (See e.g., Examples 11, and 12). In some embodiments, clonal variants are sequences that differ by one or more nucleotides or amino acids, and have a V region with shared mutations compared to the germline, identical VDJ or VJ gene usage, identical the same or similar HCDR3 length, and the same VL and JL usage. The germline sequence (unmutated common ancestor “UCA”) is intended to be the sequence coding for the antibody/immunoglobulin (or of any fragment thereof) deprived of mutations, for example somatic mutations. Antibodies in a clone that are designate as UCA and/or I (for “Intermediate”) are typically not isolated from a biological sample, but are derived computationally based on VH and/or VL sequences isolated from subjects infected with HIV-1.

Compositions including the human antibodies of the invention, including antibodies specific for gp41, can be used for any purpose including but not limited to research, diagnostic and therapeutic purposes. In non-limiting embodiments, the human monoclonal antibodies disclosed herein can be used to detect HIV-1 in a biological sample or interfere with the HIV-1 activity, for example to diagnose or treat a subject having an HIV-1 infection and/or AIDS. For example, the antibodies can be used to determine HIV-1 titer in a subject. The antibodies disclosed herein also can be used to study the biology of the human immunodeficiency virus. The antibodies of the invention can be used for therapeutic purposes for treatment or prevention of HIV-1 infection, alone or in combination with other therapeutic modalities, including ART and/or combination with other HIV-1 targeting antibodies, neutralizing antibodies and/or ADCC inducing antibodies.

In some embodiments, the disclosed MPER antibodies specifically bind to a polypeptide disclosed in for example but not limited to FIG. 3, FIG. 11, and FIG. 16, and Example 12. The person of ordinary skill in the art will understand that the antibodies of the invention can also bind to gp41MPER residues extending N-terminal or C-terminal to the above sequences.

In some embodiments, residues believed to make contacts with the antibodies of the invention include resides identified in the mapping studies described in for example but not limited to FIGS. 11, 16-15. In some embodiments, the antibodies of the invention are expected to make contact with additional gp41 MPER residues. In some embodiments, the antibodies of the invention are expected to make contact with some of the gp41 MPER residues as previously described for the 10E8 antibody.

In some embodiments, the disclosed antibodies are referred to as 10E8-like antibodies because their binding to the MPER maps to a region similar to the MPER region bound by the 10E8 antibody previously described (See US Pub 20140348785). The 10E8 antibody specifically binds the membrane proximal extracellular region (MPER) of gp41 at an epitope that is designated as the 10E8 epitope. The crystal structure of the 10E8 antibody was solved in complex with a gp41 peptide (See 20140348785 Example 1), which allowed for detailed analysis of the binding of the 10E8 antibody and gp41, and describe at the atomic level the binding of 10E8 antibody to the 10E8 epitope. This epitope, and thus the antibodies of this class (10E8-like antibodies), can be distinguished from other antibodies that bound gp41 at other epitopes. The 10E8 epitope, e.g., KWASLWNWFDITNWLWYIR (SEQ ID NO: 464), extends C-terminal to the 2F5 epitope (although there is some overlap) on the gp41 ectodomain and is distinguished from the 4E10 and Z13E1 epitope by expanding the binding to C-terminal residues previously thought to be inaccessible (e.g. these residues were believed to be buried in the lipid bilayer).

In some embodiments, an MPER antibody of the invention is not the 10E8, 4E10, 2F5 or any other MPER antibody as previously described. Some of the difference between certain antibodies of the invention and the 10E8, 4E10 and 2F5 antibodies are demonstrated in FIG. 15 (VH sequence alignment) and FIGS. 6, and 7 (neutralization breadth and potency), and for example but not limited to FIGS. 11, 16-25 (epitope mapping studies), Example 12. In certain embodiments, the inventive antibodies bind an MPER epitope which comprises D674 (See FIG. 11). In certain embodiments, the 10E8 antibody (See US Pub 20140348785) MPER binding is not sensitive to D674S mutation. The DH511 lineage antibodies (FIG. 6) neutralize 100% of isolates whereas 10E8 did not (FIG. 7).

In some embodiments, the antibodies of the invention are expected not to exhibit self-reactivity—they do not bind or bind very weakly to self-antigens, such as human protein. For use as preventive or therapeutic agents, what matters is whether the mature antibody will be polyreactive or not (FIGS. 35-36, Example 12). Various assays to determine poly and autoreactivity are known in the art.

The neutralization breadth of the inventive antibodies is demonstrated by the diversity of viruses which are neutralized in the TZMbl Env pseudovirus inhibition assay. In certain embodiments, the neutralization breadth and/or binding of the antibodies of the invention can be maintained in the presence of tolerate changes to the epitope. Comparing the sequences of the neutralized viruses, versus viruses that are not neutralized, a skilled artisan can readily determine the % virus changes, including changes in the MPER region and the epitope, which can be tolerated while neutralization and/or binding is maintained.

Comparing the sequences of the antibodies (e.g. FIGS. 4, 12, 13, 14 and 15) and their neutralization properties (e.g. FIGS. 6-9), a skilled artisan can readily determine sequence identity, compare sequence length and determine the % sequence identity and/or changes, including % sequence identity and/or changes in the VH and VL sequences, including % sequence identity and/or changes in the CDRs, as well as the specific positions and types of substitutions which can be tolerated while neutralization potency and breadth is maintained.

Various algorithms for sequence alignment are known in the art. The similarity between amino acid sequences is expressed in terms of the similarity between the sequences, otherwise referred to as sequence identity. Sequence identity is frequently measured in terms of percentage identity (or similarity or homology); the higher the percentage, the more similar the two sequences are. Homologs or variants of a polypeptide will possess a relatively high degree of sequence identity when aligned using standard methods.

Methods of alignment of sequences for comparison are well known in the art. Various programs and alignment algorithms are described in: Smith and Waterman, Adv. Appl. Math. 2:482, 1981; Needleman and Wunsch, J. Mol. Biol. 48:443, 1970; Pearson and Lipman, Proc. Natl. Acad. Sci. U.S.A. 85:2444, 1988; Higgins and Sharp, Gene 73:237, 1988; Higgins and Sharp, CABIOS 5:151, 1989; Corpet et al., Nucleic Acids Research 16:10881, 1988; and Pearson and Lipman, Proc. Natl. Acad. Sci. U.S.A. 85:2444, 1988. Altschul et al., Nature Genet. 6:119, 1994, presents a detailed consideration of sequence alignment methods and homology calculations.

The NCBI Basic Local Alignment Search Tool (BLAST) (Altschul et al., J. Mol. Biol. 215:403, 1990) is available from several sources, including the National Center for Biotechnology Information (NCBI, Bethesda, Md.) and on the internet, for use in connection with the sequence analysis programs blastp, blastn, blastx, tblastn and tblastx. A description of how to determine sequence identity using this program is available on the NCBI website on the internet.

Homologs and variants of a VL or a VH of an antibody that specifically binds a polypeptide are typically characterized by possession of at least about 75%, for example at least about 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% sequence identity counted over the full length alignment with the amino acid sequence of interest. Proteins with even greater similarity to the reference sequences will show increasing percentage identities when assessed by this method, such as at least 80%, at least 85%, at least 90%, at least 95%, at least 98%, or at least 99% sequence identity. When less than the entire sequence is being compared for sequence identity, homologs and variants will typically possess at least 80% sequence identity over short windows of 10-20 amino acids, and may possess sequence identities of at least 85% or at least 90% or 95% depending on their similarity to the reference sequence. Methods for determining sequence identity over such short windows are available at the NCBI website on the internet. One of skill in the art will appreciate that these sequence identity ranges are provided for guidance only; it is entirely possible that strongly significant homologs could be obtained that fall outside of the ranges provided.

In certain embodiments, the invention provides antibodies which are 99%, 98%, 97%, 96%, 95%, 94%, 93%, 92%, 91%, 90%, 89%, 88%, 87%, 86%, 85%, 84%, 83%, 82%, 81%, 80% identical to the VH and VL amino acid sequences of the antibodies described herein and still maintain the neutralization breadth, biding and/or potency. In certain embodiments, the invention provides antibodies which are 99%, 98%, 97%, 96%, 95%, 94%, 93%, 92%, 91%, 90%, 89%, 88%, 87%, 86%, 85%, 84%, 83%, 82%, 81%, 80% identical to the CDR1, 2, and/or 3 of VH and CDR1, 2, and/or 3 VL amino acid sequences of the antibodies described herein and still maintain the neutralization breadth, biding and/or potency.

In certain embodiments, the invention provides antibodies which can tolerate a larger percent variation in the sequences outside of the VH and/VL sequences of the antibodies. In certain embodiments, the invention provides antibodies which are 99%, 98%, 97%, 96%, 95%, 94%, 93%, 92%, 91%, 90%, 89%, 88%, 87%, 86%, 85%, 84%, 83%, 82%, 81%, 80%, 79%, 78%, 77%, 76%, 75%, 74%, 73%, 72%, 71%, 70%, 69%, 68%, 67%, 66%, 65% identical, wherein the identity is outside of the VH or VL regions, or the CDRs of the VH or VL chains of the antibodies described herein.

Antibodies exist, for example as intact immunoglobulins and antigen binding variants or fragments e.g. as a number of well characterized produced by digestion with various peptidases. For instance, Fabs, Fvs, scFvs that specifically bind to gp41 or fragments of gp41 would be gp41-specific binding agents. Binding specificity can be determined by any suitable assay in the art, for example but not limited competition binding assays, epitope mapping, etc. A scFv protein is a fusion protein in which a light chain variable region of an immunoglobulin and a heavy chain variable region of an immunoglobulin are bound by a linker, while in dsFvs, the chains have been mutated to introduce a disulfide bond to stabilize the association of the chains. Provided are also genetically engineered forms such as chimeric antibodies and heteroconjugate antibodies such as bispecific antibodies. See also, Pierce Catalog and Handbook, 1994-1995 (Pierce Chemical Co., Rockford, Ill.); Kuby, Immunology, 3.sup.rd Ed., W.H. Freeman & Co., New York, 1997.

In certain embodiments the invention provides antibody fragments, which have the binding specificity and/or properties of the inventive antibodies. Non-limiting examples include: (1) Fab, the fragment which contains a monovalent antigen-binding fragment of an antibody molecule produced by digestion of whole antibody with the enzyme papain to yield an intact light chain and a portion of one heavy chain; (2) Fab′, the fragment of an antibody molecule obtained by treating whole antibody with pepsin, followed by reduction, to yield an intact light chain and a portion of the heavy chain; two Fab′ fragments are obtained per antibody molecule; (3) (Fab′).sub.2, the fragment of the antibody obtained by treating whole antibody with the enzyme pepsin without subsequent reduction; (4) F(ab′).sub.2, a dimer of two Fab′ fragments held together by two disulfide bonds; (5) Fv, a genetically engineered fragment containing the variable region of the light chain and the variable region of the heavy chain expressed as two chains; and (6) single chain antibody (“SCA”), a genetically engineered molecule containing the variable region of the light chain, the variable region of the heavy chain, linked by a suitable polypeptide linker as a genetically fused single chain molecule. In certain embodiments, the antibody fragments can be produces recombinantly.

In certain embodiments, VH refers to the variable region of an immunoglobulin heavy chain, including but not limited to that of an antibody fragment, such as Fv, scFv, dsFv or Fab. In certain embodiments, VL refers to the variable region of an immunoglobulin light chain, including but not limited to that of an Fv, scFv, dsFv or Fab.

Any of the nucleic acids encoding any of the antibodies, or fragment thereof can be expressed in a recombinantly engineered cell such as bacteria, plant, yeast, insect and mammalian cells. The nucleic acid sequences include any sequence necessary for expression, including but not limited to a promoter, a leader sequence. These antibodies can be expressed as individual VH and/or VL chain, or can be expressed as a fusion protein. In certain embodiments, the antibodies can be expressed by viral vector mediated delivery of genes encoding the antibodies of the invention (See e.g. Yang et al. Viruses 2014, 6, 428-447).

To create a single chain antibody, (scFv) the VH- and VL-encoding DNA fragments are operatively linked to another fragment encoding a flexible linker, e.g., encoding the amino acid sequence (Gly₄-Ser)₃ (SEQ ID NO: 470), such that the VH and VL sequences can be expressed as a contiguous single-chain protein, with the VH and VL domains joined by the flexible linker (see, e.g., Bird et al., Science 242:423-426, 1988; Huston et al., Proc. Natl. Acad. Sci. USA 85:5879-5883, 1988; McCafferty et al., Nature 348:552-554, 1990). Optionally, a cleavage site can be included in a linker, such as a furin cleavage site.

In some embodiments, a single chain antibody may be monovalent, if only a single VH and VL are used, bivalent, if two VH and VL are used, or polyvalent, if more than two VH and VL are used. Bispecific or polyvalent antibodies may be generated that bind specifically to gp120 and to another molecule, such as gp41.

There are numerous expression systems available for expression of proteins including E. coli, other bacterial hosts, yeast, and various higher eukaryotic cells such as the COS, CHO, HeLa and myeloma cell lines.

In certain embodiments, the invention provides monoclonal antibodies. In certain embodiments the monoclonal antibodies are produced by a clone of B-lymphocytes. In certain embodiments the monoclonal antibody is a recombinant and is produced by a host cell into which the light and heavy chain genes of a single antibody have been transfected. Any suitable cell could be used for transfection and expression of the antibodies of the invention. Suitable cell lines include without limitation 293T cells or CHO cells.

Monoclonal antibodies are produced by any suitable method known to those of skill in the art. In some embodiments, monoclonal antibodies are produced by immortalizing B-cell expressing an antibody. Methods for immortalizing B-cells are known in the art, for example but not limited to using EBV transformation, treatment with various stimulants, and/or apoptotic inhibitors (Bonsignori et al. J. Virol. 85: 9998-10009, 2011). In some embodiments, monoclonal antibodies are produced by making hybrid antibody-forming cells from a fusion of myeloma cells with immune spleen cells to make hybridomas. In some embodiments monoclonal antibodies are isolated from a subject, for example but not limited as described in Example 1 (Liao H X et al. J Virol Methods. 2009 June; 158(1-2):171-9). The amino acid and nucleic acid sequences of such monoclonal antibodies can be determined.

The antibodies described herein, or fragments thereof, may be recombinantly produced in prokaryotic or eukaryotic expression systems. These systems are well described in the art. In general, protein therapeutics are produced from mammalian cells. The most widely used host mammalian cells are Chinese hamster ovary (CHO) cells and mouse myeloma cells, including NS0 and Sp2/0 cells. Two derivatives of the CHO cell line, CHO-K1 and CHO pro-3, gave rise to the two most commonly used cell lines in large scale production, DUKX-X11 and DG44. (See, e.g., Kim, J., et al., “CHO cells in biotechnology for production of recombinant proteins: current state and further potential,” Appl. Microbiol. Biotechnol., 2012, 93:917-30, which is hereby incorporated-by-reference.) Other mammalian cell lines for recombinant antibody expression include, but are not limited to, COS, HeLa, HEK293T, U2O5, A549, HT1080, CAD, P19, NIH 3T3, L929, N2a, HEK 293, MCF-7, Y79, SO-Rb50, HepG2, J558L, and BHK. If the aim is large-scale production, the most currently used cells for this application are CHO cells. Guidelines to cell engineering for mAbs production were also reported. (Costa et al., “Guidelines to cell engineering for monoclonal antibody production,” Eur J Pharm Biopharm, 2010, 74:127-38, which is hereby incorporated-by-reference.) Using heterologous promoters, enhancers and amplifiable genetic markers, the yields of antibody and antibody fragments can be increased. Thus, in certain embodiments, the invention provides an antibody, or antibody fragment, that is recombinantly produced from a mammalian cell-line, including a CHO cell-line. In certain embodiments, the invention provides a composition comprising an antibody, or antibody fragment, wherein the antibody or antibody fragment was recombinantly produced in a mammalian cell-line, and wherein the antibody or antibody fragment is present in the composition at a concentration of at least 1, 10, 100, 1000 micrograms/mL, or at a concentration of at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 50, or 100 milligrams/mL.

Furthermore, large-scale production of therapeutic-grade antibodies are much different than those for laboratory scale. There are extreme purity requirements for therapeutic-grade. Large-scale production of therapeutic-grade antibodies requires multiples steps, including product recovery for cell-culture harvest (removal of cells and cell debris), one or more chromatography steps for antibody purification, and formulation (often by tangential filtration). Because mammalian cell culture and purification steps can introduce antibody variants that are unique to the recombinant production process (i.e., antibody aggregates, N- and C-terminal variants, acidic variants, basic variants, different glycosylation profiles), there are recognized approaches in the art for analyzing and controlling these variants. (See, Fahrner, et al., Industrial purification of pharmaceutical antibodies: Development, operation, and validation of chromatography processes, Biotech. Gen. Eng. Rev., 2001, 18:301-327, which is hereby incorporated-by-reference.) In certain embodiments of the invention, the antibody composition comprises less than 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 35, 50, or 100 nanograms of host cell protein (i.e., proteins from the cell-line used to recombinantly produce the antibody)). In other embodiments, the antibody composition comprises less than 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, or 25 ng of protein A per milligram of antibody or antibody fragment (i.e., protein A is a standard approach for purifying antibodies from recombinant cell culture, but steps should be done to limit the amount of protein A in the composition, as it may be immunogenic). (See, e.g., U.S. Pat. No. 7,458,704, Reduced protein A leaching during protein A affinity chromatography; which is hereby incorporated-by-reference.)

The antibodies of the invention can be of any isotype. In certain embodiments, the antibodies of the invention can be used as IgG1, IgG2, IgG3, IgG4, whole IgG1 or IgG3s, whole monomeric IgAs, dimeric IgAs, secretory IgAs, IgMs as monomeric, pentameric or other polymer forms of IgM. The class of an antibody comprising the VH and VL chains described herein can be specifically switched to a different class of antibody by methods known in the art.

In some embodiments, the nucleic acid encoding the VH and VL can encode an Fc domain (immunoadhesin). The Fc domain can be an IgA, IgM or IgG Fc domain. The Fc domain can be an optimized Fc domain, as described in U.S. Published Patent Application No. 20100093979, incorporated herein by reference. In one example, the immunoadhesin is an IgG1 Fc. In one example, the immunoadhesin is an IgG3 Fc.

In certain embodiments the antibodies comprise amino acid alterations, or combinations thereof, for example in the Fc region outside of epitope binding, which alterations can improve their properties. Various Fc modifications are known in the art. Amino acid numbering is according to the EU Index in Kabat. In some embodiments, the invention contemplates antibodies comprising mutations that affect neonatal Fc receptor (FcRn) binding, antibody half-life, and localization and persistence of antibodies at mucosal sites. See e.g. Ko S Y et al., Nature 514: 642-45, 2014, at FIG. 1a and citations therein; Kuo, T. and Averson, V., mAbs 3(5): 422-430, 2011, at Table 1, US Pub 20110081347 (an aspartic acid at Kabat residue 288 and/or a lysine at Kabat residue 435), US Pub 20150152183 for various Fc region mutation, incorporated by reference in their entirety. In certain embodiments, the antibodies comprise AAAA substitution in and around the Fc region of the antibody that has been reported to enhance ADCC via NK cells (AAA mutations) containing the Fc region aa of S298A as well as E333A and K334A (Shields R I et al JBC, 276: 6591-6604, 2001) and the 4^(th) A (N434A) is to enhance FcR neonatal mediated transport of the IgG to mucosal sites (Shields R I et al. ibid). Other antibody mutations have been reported to improve antibody half-life or function or both and can be incorporated in sequences of the antibodies. These include the DLE set of mutations (Romain G, et al. Blood 124: 3241, 2014), the LS mutations M428L/N434S, alone or in a combination with other Fc region mutations, (Ko S Y et al. Nature 514: 642-45, 2014, at FIG. 1a and citations therein; Zlevsky et al., Nature Biotechnology, 28(2): 157-159, 2010; US Pub 20150152183); the YTE Fc mutations (Robbie G et al Antimicrobial Agents and Chemotherapy 12: 6147-53, 2013) as well as other engineered mutations to the antibody such as QL mutations, IHH mutations (Ko S Y et al. Nature 514: 642-45, 2014, at FIG. 1a and relevant citations; See also Rudicell R et al. J. Virol 88: 12669-82, 201). In some embodiments, modifications, such as but not limited to antibody fucosylation, may affect interaction with Fc receptors (See e.g. Moldt, et al. JVI 86(11): 66189-6196, 2012). In some embodiments, the antibodies can comprise modifications, for example but not limited to glycosylation, which reduce or eliminate polyreactivity of an antibody. See e.g. Chuang, et al. Protein Science 24: 1019-1030, 2015. In some embodiments the antibodies can comprise modifications in the Fc domain such that the Fc domain exhibits, as compared to an unmodified Fc domain enhanced antibody dependent cell mediated cytotoxicity (ADCC); increased binding to Fc.gamma.RIIA or to Fc.gamma.RIIIA; decreased binding to Fc.gamma.RIIB; or increased binding to Fc.gamma.RIIB. See e.g. US Pub 20140328836.

In certain embodiments, antibodies of the invention including but not limited to antibodies comprising a CDR(s) of VH and/or VL chains, or antibody fragments of the inventive antibodies can be used as the HIV-1 binding arm(s) of a bispecific molecule, e.g. DARTS, diabodies, toxin labeled HIV-1 binding molecules.

In accordance with the methods of the present invention, either the intact antibody or a fragment thereof can be used. Either single chain Fv, bispecific antibody for T cell engagement, or chimeric antigen receptors can be used (Chow et al, Adv. Exp. Biol. Med. 746:121-41 (2012)). That is, in non-limiting embodiments, intact antibody, a Fab fragment, a diabody, or a bispecific whole antibody can be used to inhibit HIV-1 infection in a subject (e.g., a human). A bispecific F(ab)2 can also be used with one arm a targeting molecule like CD3 to deliver it to T cells and the other arm the arm of the native antibody (Chow et al, Adv. Exp. Biol. Med. 746:121-41 (2012)). Toxins that can be bound to the antibodies or antibody fragments described herein include unbound antibody, radioisotopes, biological toxins, boronated dendrimers, and immunoliposomes (Chow et al, Adv. Exp. Biol. Med. 746:121-41 (2012)). Toxins (e.g., radionucleotides or other radioactive species) can be conjugated to the antibody or antibody fragment using methods well known in the art (Chow et al, Adv. Exp. Biol. Med. 746:121-41 (2012)). The invention also includes variants of the antibodies (and fragments) disclosed herein, including variants that retain the ability to bind to recombinant Env protein, the ability to bind to the surface of virus-infected cells and/or ADCC-mediating properties of the antibodies specifically disclosed, and methods of using same to, for example, reduce HIV-1 infection risk. Combinations of the antibodies, or fragments thereof, disclosed herein can also be used in the methods of the invention.

Antibodies of the invention and fragments thereof can be produced recombinantly using nucleic acids comprising nucleotide sequences encoding VH and VL sequences selected from those shown in the figures and examples.

In certain embodiments the invention provides intact/whole antibodies. In certain embodiments the invention provides antigen binding fragments thereof. Typically, fragments compete with the intact antibody from which they were derived for specific binding to the target including separate heavy chains, light chains Fab, Fab′, F(ab′).sub.2, F(ab)c, diabodies, Dabs, nobodies, and Fv. Fragments can be produced by recombinant DNA techniques, or by enzymatic or chemical separation of intact immunoglobulins.

In certain embodiments the invention provides a bispecific antibody. A bispecific or bifunctional/dual targeting antibody is an artificial hybrid antibody having two different heavy/light chain pairs and two different binding sites (see, e.g., Romain Rouet & Daniel Christ “Bispecific antibodies with native chain structure” Nature Biotechnology 32, 136-137 (2014); Garber “Bispecific antibodies rise again” Nature Reviews Drug Discovery 13, 799-801 (2014), FIG. 1a ; Byrne et al. “A tale of two specificities: bispecific antibodies for therapeutic and diagnostic applications” Trends in Biotechnology, Volume 31, Issue 11, November 2013, Pages 621-632 Songsivilai and Lachmann, Clin. Exp. Immunol., 79:315-321 (1990); Kostelny et al., J. Immunol. 148:1547-53 (1992) (and references therein)). In certain embodiments the bispecific antibody is a whole antibody of any isotype. In other embodiments it is a bispecific fragment, for example but not limited to F(ab)2 fragment. In some embodiments, the bispecific antibodies do not include Fc portion, which makes these diabodies relatively small in size and easy to penetrate tissues.

In certain embodiments, the bispecific antibodies could include Fc region. Fc bearing diabodies, for example but not limited to Fc bearing DARTs are heavier, and could bind neonatal Fc receptor, increasing their circulating half-life. See Garber “Bispecific antibodies rise again” Nature Reviews Drug Discovery 13, 799-801 (2014), FIG. 1a ; See US Pub 20130295121, incorporated by reference in their entirety. In certain embodiments, the invention encompasses diabody molecules comprising an Fc domain or portion thereof (e.g. a CH2 domain, or CH3 domain). The Fc domain or portion thereof may be derived from any immunoglobulin isotype or allotype including, but not limited to, IgA, IgD, IgG, IgE and IgM. In some embodiments, the Fc domain (or portion thereof) is derived from IgG. In some embodiments, the IgG isotype is IgG1, IgG2, IgG3 or IgG4 or an allotype thereof. In some embodiments, the diabody molecule comprises an Fc domain, which Fc domain comprises a CH2 domain and CH3 domain independently selected from any immunoglobulin isotype (i.e. an Fc domain comprising the CH2 domain derived from IgG and the CH3 domain derived from IgE, or the CH2 domain derived from IgG1 and the CH3 domain derived from IgG2, etc.). In some embodiments, the Fc domain may be engineered into a polypeptide chain comprising the diabody molecule of the invention in any position relative to other domains or portions of the polypeptide chain (e.g., the Fc domain, or portion thereof, may be c-terminal to both the VL and VH domains of the polypeptide of the chain; may be n-terminal to both the VL and VH domains; or may be N-terminal to one domain and c-terminal to another (i.e., between two domains of the polypeptide chain)).

The present invention also encompasses molecules comprising a hinge domain. The hinge domain be derived from any immunoglobulin isotype or allotype including IgA, IgD, IgG, IgE and IgM. In preferred embodiments, the hinge domain is derived from IgG, wherein the IgG isotype is IgG1, IgG2, IgG3 or IgG4, or an allotype thereof. The hinge domain may be engineered into a polypeptide chain comprising the diabody molecule together with an Fc domain such that the diabody molecule comprises a hinge-Fc domain. In certain embodiments, the hinge and Fc domain are independently selected from any immunoglobulin isotype known in the art or exemplified herein. In other embodiments the hinge and Fc domain are separated by at least one other domain of the polypeptide chain, e.g., the VL domain. The hinge domain, or optionally the hinge-Fc domain, may be engineered in to a polypeptide of the invention in any position relative to other domains or portions of the polypeptide chain. In certain embodiments, a polypeptide chain of the invention comprises a hinge domain, which hinge domain is at the C-terminus of the polypeptide chain, wherein the polypeptide chain does not comprise an Fc domain. In yet other embodiments, a polypeptide chain of the invention comprises a hinge-Fc domain, which hinge-Fc domain is at the C-terminus of the polypeptide chain. In further embodiments, a polypeptide chain of the invention comprises a hinge-Fc domain, which hinge-Fc domain is at the N-terminus of the polypeptide chain.

In some embodiments, the invention encompasses multimers of polypeptide chains, each of which polypeptide chains comprise a VH and VL domain, comprising CDRs as described herein. In certain embodiments, the VL and VH domains comprising each polypeptide chain have the same specificity, and the multimer molecule is bivalent and monospecific. In other embodiments, the VL and VH domains comprising each polypeptide chain have differing specificity and the multimer is bivalent and bispecific. In some embodiments, the polypeptide chains in multimers further comprise an Fc domain. Dimerization of the Fc domains leads to formation of a diabody molecule that exhibits immunoglobulin-like functionality, i.e., Fc mediated function (e.g., Fc-Fc.gamma.R interaction, complement binding, etc.).

In yet other embodiments, diabody molecules of the invention encompass tetramers of polypeptide chains, each of which polypeptide chain comprises a VH and VL domain. In certain embodiments, two polypeptide chains of the tetramer further comprise an Fc domain. The tetramer is therefore comprised of two ‘heavier’ polypeptide chains, each comprising a VL, VH and Fc domain, and two ‘lighter’ polypeptide chains, comprising a VL and VH domain. Interaction of a heavier and lighter chain into a bivalent monomer coupled with dimerization of the monomers via the Fc domains of the heavier chains will lead to formation of a tetravalent immunoglobulin-like molecule. In certain aspects the monomers are the same, and the tetravalent diabody molecule is monospecific or bispecific. In other aspects the monomers are different, and the tetra valent molecule is bispecific or tetraspecific.

Formation of a tetraspecific diabody molecule as described supra requires the interaction of four differing polypeptide chains. Such interactions are difficult to achieve with efficiency within a single cell recombinant production system, due to the many variants of potential chain mispairings. One solution to increase the probability of mispairings, is to engineer “knobs-into-holes” type mutations into the desired polypeptide chain pairs. Such mutations favor heterodimerization over homodimerization. For example, with respect to Fc-Fc-interactions, an amino acid substitution (preferably a substitution with an amino acid comprising a bulky side group forming a ‘knob’, e.g., tryptophan) can be introduced into the CH2 or CH3 domain such that steric interference will prevent interaction with a similarly mutated domain and will obligate the mutated domain to pair with a domain into which a complementary, or accommodating mutation has been engineered, i.e., ‘the hole’ (e.g., a substitution with glycine). Such sets of mutations can be engineered into any pair of polypeptides comprising the diabody molecule, and further, engineered into any portion of the polypeptides chains of the pair. Methods of protein engineering to favor heterodimerization over homodimerization are well known in the art, in particular with respect to the engineering of immunoglobulin-like molecules, and are encompassed herein (see e.g., Ridgway et al. (1996) “‘Knobs-Into-Holes’ Engineering Of Antibody CH3 Domains For Heavy Chain Heterodimerization,” Protein Engr. 9:617-621, Atwell et al. (1997) “Stable Heterodimers From Remodeling The Domain Interface Of A Homodimer Using A Phage Display Library,” J. Mol. Biol. 270: 26-35, and Xie et al. (2005) “A New Format Of Bispecific Antibody: Highly Efficient Heterodimerization, Expression And Tumor Cell Lysis,” J. Immunol. Methods 296:95-101; each of which is hereby incorporated herein by reference in its entirety).

The invention also encompasses diabody molecules comprising variant Fc or variant hinge-Fc domains (or portion thereof), which variant Fc domain comprises at least one amino acid modification (e.g. substitution, insertion deletion) relative to a comparable wild-type Fc domain or hinge-Fc domain (or portion thereof). Molecules comprising variant Fc domains or hinge-Fc domains (or portion thereof) (e.g., antibodies) normally have altered phenotypes relative to molecules comprising wild-type Fc domains or hinge-Fc domains or portions thereof. The variant phenotype may be expressed as altered serum half-life, altered stability, altered susceptibility to cellular enzymes or altered effector function as assayed in an NK dependent or macrophage dependent assay. Fc domain variants identified as altering effector function are known in the art. For example International Application WO04/063351, U.S. Patent Application Publications 2005/0037000 and 2005/0064514.

The bispecific diabodies of the invention can simultaneously bind two separate and distinct epitopes. In certain embodiments the epitopes are from the same antigen. In other embodiments, the epitopes are from different antigens. In preferred embodiments, at least one epitope binding site is specific for a determinant expressed on an immune effector cell (e.g. CD3, CD16, CD32, CD64, etc.) which are expressed on T lymphocytes, natural killer (NK) cells or other mononuclear cells. In one embodiment, the diabody molecule binds to the effector cell determinant and also activates the effector cell. In this regard, diabody molecules of the invention may exhibit Ig-like functionality independent of whether they further comprise an Fc domain (e.g., as assayed in any effector function assay known in the art or exemplified herein (e.g., ADCC assay).

Non-limiting examples of bispecific antibodies can also be (1) a dual-variable-domain antibody (DVD-Ig), where each light chain and heavy chain contains two variable domains in tandem through a short peptide linkage (Wu et al., Generation and Characterization of a Dual Variable Domain Immunoglobulin (DVD-Ig™) Molecule, In: Antibody Engineering, Springer Berlin Heidelberg (2010)); (2) a Tandab, which is a fusion of two single chain diabodies resulting in a tetravalent bispecific antibody that has two binding sites for each of the target antigens; (3) a flexibody, which is a combination of scFvs with a diabody resulting in a multivalent molecule; (4) a so called “dock and lock” molecule, based on the “dimerization and docking domain” in Protein Kinase A, which, when applied to Fabs, can yield a trivalent bispecific binding protein consisting of two identical Fab fragments linked to a different Fab fragment; (5) a so-called Scorpion molecule, comprising, e.g., two scFvs fused to both termini of a human Fc-region. Examples of platforms useful for preparing bispecific antibodies include but are not limited to BiTE (Micromet), DART (MacroGenics) (e.g. U.S. Pat. No. 8,795,667; U.S. Publication Nos. 2014-0099318; 2013-0295121; 2010-0174053 and 2009-0060910; European Patent Publication No. EP 2714079; EP 2601216; EP 2376109; EP 2158221 and PCT Publications No. WO 2015/026894; WO 2015/026892; WO 2015/021089; WO 2014/159940; WO 2012/162068; WO 2012/018687; WO 2010/080538), the content of each of these publications in herein incorporated by reference in its entirety), Fcab and Mab2 (F-star), Fc-engineered IgG1 (Xencor) or DuoBody (based on Fab arm exchange, Genmab).

In certain embodiments, the bispecific antibody comprises an HIV envelope binding fragment, for example but not limited to an HIV envelope binding fragment from any of the antibodies described herein. In other embodiments, the bispecific antibody further comprises a second antigen-interaction-site/fragment. In other embodiments, the bispecific antibody further comprises at least one effector domain.

In certain embodiments the bispecific antibodies engage cells for Antibody-Dependent Cell-mediated Cytotoxicity (ADCC). In certain embodiments the bispecific antibodies engage natural killer cells, neutrophil polymorphonuclear leukocytes, monocytes and macrophages. In certain embodiments the bispecific antibodies are T-cell engagers. In certain embodiments, the bispecific antibody comprises an HIV envelope binding fragment and CD3 binding fragment. Various CD3 antibodies are known in the art. See for example U.S. Pat. No. 8,784,821. In certain embodiments, the bispecific antibody comprises an HIV envelope binding fragment and CD16 binding fragment.

In certain embodiments the invention provides antibodies with dual targeting specificity. In certain aspects the invention provides bi-specific molecules that are capable of localizing an immune effector cell to an HIV-1 envelope expressing cell, so as facilitate the killing of the HIV-1 envelope expressing cell. In this regard, bispecific antibodies bind with one “arm” to a surface antigen on target cells, and with the second “arm” to an activating, invariant component of the T cell receptor (TCR) complex. The simultaneous binding of such an antibody to both of its targets will force a temporary interaction between target cell and T cell, causing activation of any cytotoxic T cell and subsequent lysis of the target cell. Hence, the immune response is re-directed to the target cells and is independent of peptide antigen presentation by the target cell or the specificity of the T cell as would be relevant for normal MHC-restricted activation of CTLs. In this context it is crucial that CTLs are only activated when a target cell is presenting the bispecific antibody to them, i.e. the immunological synapse is mimicked. Particularly desirable are bispecific antibodies that do not require lymphocyte preconditioning or co-stimulation in order to elicit efficient lysis of target cells.

Several bispecific antibody formats have been developed and their suitability for T cell mediated immunotherapy investigated. Out of these, the so-called BiTE (bispecific T cell engager) molecules have been very well characterized and already shown some promise in the clinic (reviewed in Nagorsen and Bauerle, Exp Cell Res 317, 1255-1260 (2011)). BiTEs are tandem scFv molecules wherein two scFv molecules are fused by a flexible linker. Further bispecific formats being evaluated for T cell engagement include diabodies (Holliger et al., Prot Eng 9, 299-305 (1996)) and derivatives thereof, such as tandem diabodies (Kipriyanov et al., J Mol Biol 293, 41-66 (1999)). DART (dual affinity retargeting) molecules are based on the diabody format but feature a C-terminal disulfide bridge for additional stabilization (Moore et al., Blood 117, 4542-51 (2011)). The so-called triomabs, which are whole hybrid mouse/rat IgG molecules and also currently being evaluated in clinical trials, represent a larger sized format (reviewed in Seimetz et al., Cancer Treat Rev 36, 458-467 (2010)).

The invention also contemplates bispecific molecules with enhanced pharmacokinetic properties. In some embodiments, such molecules are expected to have increased serum half-life. In some embodiments, these are Fc-bearing DARTs (see supra).

In certain embodiments, such bispecific molecules comprise one portion which targets HIV-1 envelope and a second portion which binds a second target. In certain embodiments, the first portion comprises VH and VL sequences, or CDRs from the antibodies described herein. In certain embodiments, the second target could be, for example but not limited to an effector cell. In certain embodiments the second portion is a T-cell engager. In certain embodiments, the second portion comprises a sequence/paratope which targets CD3. In certain embodiments, the second portion is an antigen-binding region derived from a CD3 antibody, optionally a known CD3 antibody. In certain embodiments, the anti-CD antibody induce T cell-mediated killing. In certain embodiments, the bispecific antibodies are whole antibodies. In other embodiments, the dual targeting antibodies consist essentially of Fab fragments. In other embodiments, the dual targeting antibodies comprise a heavy chain constant region (CH1. In certain embodiments, the bispecific antibody does not comprise Fc region. In certain embodiments, the bispecific antibodies have improved effector function. In certain embodiments, the bispecific antibodies have improved cell killing activity. Various methods and platforms for design of bispecific antibodies are known in the art. See for example US Pub. 20140206846, US Pub. 20140170149, US Pub. 20090060910, US Pub 20130295121, US Pub. 20140099318, US Pub. 20140088295 which contents are herein incorporated by reference in their entirety.

In certain embodiments the invention provides human, humanized and/or chimeric antibodies.

Pharmaceutical Compositions

In certain aspects the invention provides a pharmaceutical composition comprising an antibody of the invention wherein the composition is used for therapeutic purposes such as but not limited to prophylaxis, treatments, prevention, and/or cure. In certain aspects the invention provides a pharmaceutical composition comprising an antibody of the invention in combination with any other suitable antibody. In certain embodiments, the pharmaceutical compositions comprise nucleic acids which encode the antibodies of the invention. In certain embodiments, these nucleic acids can be expressed by any suitable vector for expression of antibodies. Non-limiting examples include attenuated viral hosts or vectors or bacterial vectors, recombinant vaccinia virus, adenovirus, adeno-associated virus (AAV), herpes virus, retrovirus, cytomegalovirus or other viral vectors can be used to express the antibody.

Various methods to make pharmaceutical compositions are known in the art and are contemplated by the invention. In some embodiments, the compositions include excipient suitable for a biologic molecule such as the antibodies of the invention. In some embodiments, the antibodies could be produced in specific cell lines and conditions so as to control glycosylation of the antibody. In some embodiments, the antibody framework for example, could comprise specific modification so as to increase stability of the antibody.

In certain aspects, the invention provides that the antibodies, and fragments thereof, described herein can be formulated as a composition (e.g., a pharmaceutical composition). Suitable compositions can comprise an inventive antibody (or antibody fragment) dissolved or dispersed in a pharmaceutically acceptable carrier (e.g., an aqueous medium). The compositions can be sterile and can be in an injectable form (e.g. but not limited to a form suitable for intravenous injection, intramascular injection). The antibodies (and fragments thereof) can also be formulated as a composition appropriate for topical administration to the skin or mucosa. Such compositions can take the form of liquids, ointments, creams, gels and pastes. The antibodies (and fragments thereof) can also be formulated as a composition appropriate for intranasal administration. The antibodies (and fragments thereof) can be formulated so as to be administered as a post-coital douche or with a condom. Standard formulation techniques can be used in preparing suitable compositions.

The antibody (and fragments thereof), described herein have utility, for example, in settings including but not limited to the following:

i) in the setting of anticipated known exposure to HIV-1 infection, the antibodies described herein (or fragments thereof) and be administered prophylactically (e.g., IV, topically or intranasally) as a microbiocide,

ii) in the setting of known or suspected exposure, such as occurs in the setting of rape victims, or commercial sex workers, or in any homosexual or heterosexual transmission without condom protection, the antibodies described herein (or fragments thereof) can be administered as post-exposure prophylaxis, e.g., IV or topically, and

iii) in the setting of Acute HIV infection (AHI), the antibodies described herein (or fragments thereof) can be administered as a treatment for AHI to control the initial viral load or for the elimination of virus-infected CD4 T cells.

In accordance with the invention, the antibodies (or antibody fragments) described herein can be administered prior to contact of the subject or the subject's immune system/cells with HIV-1 or within about 48 hours of such contact. Administration within this time frame can maximize inhibition of infection of vulnerable cells of the subject with HIV-1.

In addition, various forms of the antibodies described herein can be administered to chronically or acutely infected HIV patients and used to kill remaining virus infected cells by virtue of these antibodies binding to the surface of virus infected cells and being able to deliver a toxin to these reservoir cells.

Suitable dose ranges can depend on the antibody (or fragment) and on the nature of the formulation and route of administration. Optimum doses can be determined by one skilled in the art without undue experimentation. For example, doses of antibodies in the range of 1-50 mg/kg of unlabeled or labeled antibody (with toxins or radioactive moieties) can be used. If antibody fragments, with or without toxins are used or antibodies are used that can be targeted to specific CD4 infected T cells, then less antibody can be used (e.g., from 5 mg/kg to 0.01 mg/kg).

In certain aspects the invention provides use of the antibodies of the invention, including bispecific antibodies, in methods of treating and preventing HIV-1 infection in an individual, comprising administering to said individual a therapeutically effective amount of a composition comprising the antibodies of the invention in a pharmaceutically acceptable form. In certain embodiment, the methods include a composition which includes more than one HIV-1 targeting antibody. In certain embodiments, the HIV-1 targeting antibodies in such combination bind different epitopes on the HIV-1 envelope. In certain embodiments, such combinations of bispecific antibodies targeting more than one HIV-1 epitope provide increased killing of HIV-1 infected cells. In other embodiments, such combinations of bispecific antibodies targeting more than one HIV-1 epitope provide increased breadth in recognition of different HIV-1 subtypes.

In certain embodiments, the composition comprising the antibodies of the invention alone or in any combination can be administered via IM, subcutaneous, or IV delivery, or could be deposited at mucosal sites, such as the oral cavity to prevent maternal to child transmission, the rectal space or the vagina as a microbicide. In certain embodiments, the antibodies can be administered locally in the rectum, vagina, or in the oral cavity, and can be formulated as a microbiocide (Hladik F et al ELIFE Elife. 2015 Feb. 3; 4. doi: 10.7554/eLife.04525; Multipurpose prevention technologies for reproductive and sexual health. Stone A. Reprod Health Matters. 2014 November; 22(44):213-7. doi: 10.1016/S0968-8080(14)44801-8). In other embodiments, antibodies can be formulated such that the therapeutic antibody or combination thereof is impregnated on a vaginal ring (Chen Y et al. Drug Des. Devel. Ther 8: 1801-15, 2014; Malcolm R K et al BJOG 121 Suppl 5: 62-9, 2014). Antibodies can be administered alone or with anti-retroviral drugs for a combination microbiocide (Hladik F et al ELIFE Elife. 2015 Feb. 3; 4. doi: 10.7554/eLife.04525)

Alternatively they can be administered in complex with a form of HIV Env, optimally gp120, but also an Env trimer, to enhance Env immunogenicity. In certain embodiments, the antibodies can be delivered by viral vector mediated delivery of genes encoding the antibodies of the invention (See e.g. Yang et al. Viruses 2014, 6, 428-447). In certain embodiments, the antibodies can be administered in viral vector, for example but not limited to adenoassociated viral vector, for expression in muscle and plasma.

In certain embodiments, antibodies with different binding specificities are combined for use in pharmaceutical compositions and therapeutic methods. For example: CD4 binding site antibodies are combined with V3 antibodies, MPER antibodies and so forth. FIGS. 8, 9 and 10 show a selection of potent HIV-1 neutralizing antibodies which can be used in pharmaceutical compositions, and therapeutic methods. Non-limiting examples of selections of combinations of certain antibodies include: DH542, DH542_L4, DH542_QSA, DH429 and DH512 (or any of the DH512 variants); DH512 and CH31 (See US Publication 20140205607); DH512 (or any of the other DH512 variants) and DH540 (See Example 8, and this antibody will be described elsewhere); DH542, DH542_L4, DH542_QSA, DH429, DH512 and DH540; DH542, DH542_L4, DH542_QSA, DH429 and CH557; CH557 and DH512 (or any of the DH512 variants). These combinations are expected to give a greater overall potency and breadth. A polyclonal mixture of Abs is expected reduce or eliminate viral escape. It is readily understood by skilled artisans that in some embodiments a combination therapy envisions a composition which combines various antibodies. In other embodiments a combination therapy is provided wherein antibodies are administered as individual compositions, for example at different times, by different means, or at administered at different locations. In other embodiments, a combination therapy is provides wherein a therapeutic antibody or antibodies is combined with other therapeutic means, for example anti-retroviral drug cocktails, or drugs which activate latently infected HIV-1 cells.

In some embodiments, the disclosed antibodies or antigen binding fragments thereof are used to determine whether HIV-1 envelope(s) is a suitable antigen for inclusion in a vaccine composition. For example the antibodies can be used to determine whether an antigen in a vaccine composition including a gp41 immunogen assumes a conformation including an epitope bound by the inventive antibodies or fragments thereof. This can be readily determined by a method which includes contacting a sample containing the vaccine, such as a gp120 antigen, with a disclosed antibody or antigen binding fragment under conditions sufficient for formation of an immune complex, and detecting the immune complex, to detect an HIV-1 antigen including an epitope of an inventive antibody in the sample. In one example, the detection of the immune complex in the sample indicates that vaccine component, such as a HIV-1 Env antigen assumes a conformation capable of binding the antibody or antigen binding fragment.

Antibodies Names Correlation

Various antibodies names are used throughout the application. Antibodies names correlation is as follows:

Memory B cell antibodies: DH511=DH511.1; DH512=DH511.2; DH513=DH511.3; DH514=DH511.4; DH515=DH511.5; DH516=DH511.6;

Plasma antibodies: DH511_1a=DH511.7P; DH511_2a=DH511.8P; DH511_3a=DH511.9P; DH511_4a=DH511.10P; DH511_5a=DH511.11P; DH511_5a=DH511.12P.

Chimeric antibodies which combine a heavy and light chain from different antibodies are typically indicated by the designation of the heavy and light chain of each parent antibody.

Mutations in the VH chain are referenced with respect to Kabat numbering of the indicated VH chain.

The following examples are provided to illustrate particular features of certain embodiments, but the scope of the claims should not be limited to those features exemplified.

EXAMPLES Example 1: MPER Antibodies

FIG. 1 shows the three HIV infected individual plasma that was evaluated for HIV neutralizing activity and the specificities profiled by the Georgiev algorithm (Georgiev I S et al Science 340: 751-6, 2013). From this analysis we found three subjects (CH0210, CH0536, CH1244) with gp41 bnAb activity (FIG. 1).

Methods to identify and isolate MPER reactive antibodies were carried out as described in Liao H X et al. J. Virol. Methods 158: 171-9, 2009. MPER specific hooks were designed to identify to antibodies which bind to HIV-1 gp41 MPER region. Using one such hook, the MPR.03-biotin hook tetramerized (FIG. 2), with fluorophor labeled streptavidin in two colors (FIG. 3), we sorted by flow cytometry into single wells, the diagonally (that reacted with both colors hooks) reactive memory B cells (FIG. 3). B cells from 10 million PBMC were sorted and PCR was carried out according to the protocol in Liao H X et al. J. Virol. Methods 158: 171-9, 2009. PCR amplifications were carried out to amplify rearranged VH and VL fragment pairs from the diagonally sorted memory B cells (Liao et al JVM). Overlapping PCR was used to construct full length Ig heavy and Ig light linear genes comprising the rearranged VH and VL fragment pairs. RT-PCR and PCR reactions was carried out essentially as described in Liao H X et al. J. Virol. Methods 158: 171-9, 2009, see for example FIG. 1, Section 3.3. Sequence analysis of the VH and VL genes was carried out to determine the VH and VL gene usage, CDR lengths, the % mutation of HCDR3 and LCDR3. Based on this sequence analysis, one to two pairs of linear VH and VL genes were selected and made in linear cassettes (essentially as described in Liao H X et al. J. Virol. Methods 158: 171-9, 2009, see for example FIG. 1, Section 3.3) to produce recombinant monoclonal antibodies by transient transfection in 293T cells.

Pairs of VH and VL genes as selected above can also be used to produce plasmids for stable expression of recombinant antibodies.

In certain embodiments, the plasmids or linear constructs for recombinant antibody expression also comprise AAAA substitution in and around the Fc region of the antibody that has been reported to enhance ADCC via NK cells (AAA mutations) containing the Fc region aa of S298A as well as E333A and K334A (Shields R I et al JBC, 276: 6591-6604, 2001) and the 4^(th) A (N434A) is to enhance FcR neonatal mediated transport of the IgG to mucosal sites (Shields R I et al. ibid).

The antibodies of the invention were selected based on a combination of criteria including sequence analyses, and functional analyses including but not limited as neutralization breadth, and potency.

In certain embodiments, the antibodies of the invention comprise naturally rearranged VH and VL fragment pairs, wherein the rest of the Ig gene is not naturally occurring with the isolated rearranged VH and VL fragments. In certain embodiments, the antibodies of the invention are recombinantly produced by synth

FIG. 4 and Example 12 shows a summary of some of the characteristics of the recombinant MPER antibodies of the invention. DH511-DH517 are antibodies with VH and VL chains from individual CH0210. DH518 is an antibody with VH and VL chains from individual CH0536. DH536 is an antibody with VH and VL chains from individual CH1244. CH537 is an antibody with VH and VL chains from individual CH0585. DH 511-DH516 antibodies are all members of the same B cell clonal lineage (FIG. 6). FIG. 5 shows the neutralizing capacity of these antibodies with all but DH536 and DH537 able to neutralize difficult to neutralized (tier 2) HIV strains B.BG1168, C.CH505, and C.DU172). FIG. 6 shows the phylogram of the DH511 clonal lineage.

Example 2: TZMbl Neutralization Assay

TZMbl neutralization assay is a standard way to evaluate antibody breadth and potency. See Montefiori, D. Methods Mol Biol. 2009; 485:395-405; HIV-1 Env-pseudoviruses infection of TZM-bl cells. Exemplary pseudovirus neutralization assays and panels of HIV-1 pseudovirus are described for example, in Li et al., J Virol 79, 10108-10125, 2005, Seaman et al, J. Virol., 84:1439-1452, 2010; Sarzotti-Kelsoe et al., J. Immunol. Methods, 409:131-46, 2014; and WO2011/038290, each of which is incorporated by reference herein. Various HIV-1 isolates, both Tier 1 and Tier 2 viruses can be included in this assay.

The TZMbl assay was conducted to determine neutralization potency and breadth of the various antibodies of the invention on different HIV-1 pseudoviruses.

FIG. 7 shows the results of neutralization of 8 of the gp41 antibodies against a panel of 30 HIV tier 2 isolates in the TZMbl pseudovirus neutralization assay. The DH511 clonal lineage members all neutralized 100% (30/30) isolates while DH517 neutralized 50% and DH518 neutralized 83%. This in contrast to 10E8 gp41 antibody that only neutralized 29/30 isolates. FIG. 8 shows the mean IC50, IC80 and percent of isolates neutralized at an IC50<50 ug/ml and at an IC80 of <5 ug/ml (confirm). Thus, mAb DH512 is equally as potent and slightly more broad in neutralization breadth than the mAb 10E8. FIG. 9 shows other mAbs and their breadth and potency. Various figures, including without limitation, FIGS. 37, 38, 28, 56 and 34, and Figures from Example 12 show neutralization data of various antibodies against various panels of pseudoviruses.

Example 3: Epitope Mapping of MPER Antibodies

Binding of antibodies to various MPER peptides in an ELISA assay was used to map the epitopes of the MPER antibodies.

FIG. 11 shows that Antibody epitopes maps to the C-terminus of gp41 to a similar region where 10E8 binds (Huang J et al. Nature 491 406, 2012; See US Pub 20140348785). FIGS. 11, 15-25 show binding of antibodies to MPER peptide variants. These mapping studies show that the antibodies of the invention are 10E8 like Abs. In non-limiting embodiments, DH512 shows the broadest and most potent neutralization among the antibodies tested.

FIG. 12 shows an alanine substituted gp41 peptide set used to map DH517 mab and FIG. 13 shows a summary of ala mutants to which the antibody is sensitive for binding to gp41. FIGS. 14 and 15 show the VH and VL sequences of the DH511-DH516 antibodies.

FIGS. 12-13 show the nucleotide and amino acid sequences of all the certain antibodies of the invention.

FIGS. 16-25 show that DH517 displayed a unique mapping pattern in that it depends on DKW at the N terminus and several residues at the C terminus important for 10E8 binding and neutralization. Clone DH511 mAbs bound strongly to the majority of the MPER656 variants, showing decreased binding to MPER656.2 and MPER656.2dYIK683R-biotin. These data indicate that the asparagine at position 674 is critical for binding, thus providing evidence that these mAbs bind at the C-terminus.

All the antibodies used in the above Examples had the AAAA substitution in and around the Fc region of the antibody that has been reported to enhance ADCC via NK cells (AAA mutations) containing the Fc region aa of S298A as well as E333A and K334A (Shields R I et al JBC, 276: 6591-6604, 2001) and the 4^(th) A (N434A) is to enhance FcR neonatal mediated transport of the IgG to mucosal sites (Shields R I et al. ibid).

Epitope mapping studies are also described in Example 12.

Example 4: Binding Assays and Kd Determination

Kd measurements of antibody binding to HIV-1 envelope, e.g. gp41 or any other suitable peptide for the MPER antibodies, will be determined by Surface Plasmon Resonance measurements, for example using Biacore, or any other suitable technology which permits detection of interaction between two molecules in a quantitative way.

Example 5: Various Assays

Various assays for self-reactivity of human antibodies are known in the art. AtheNA Multi-Lyte ANA Plus Test System is one such assay. ELISA cardiolipin assay is another assay to measure autoreactivity.

The stability and properties of the antibodies, for example as formulated in a composition for treatment will be tested.

Animal studies (PK and PD studies) could be conducted to determine the distribution and half-life of the antibodies.

Various assays and experiments can be designed to analyze prevention, treatment and/or cure.

Example 6: Antibodies from CH235 Lineage

CH557 is one example of a CD4bs broad neutralizing HIV-1 antibody, from a series of clonal antibodies (FIG. 28) which can be used in combination with the antibodies of the invention.

Example 7: V3 Glycan Antibodies from DH270 Lineage

Antibodies from DH270 lineage are shown in FIG. 26. I1 (DH270IA1), I2, I4, I3 and UCA in FIG. 26 are not isolated from human subjects but are derived computationally based on VH and VL sequences of other observed antibodies from the clone: DH471, DH429, DH473, DH391 and DH270. The VH and VL sequences of DH471, DH429, DH473, DH391 and DH270 are derived from a human subject infected with HIV-1.

The VH and VL sequences of DH471, DH429, DH473, DH391 and DH270 are derived essentially as described in Example 1, except that cell were sorted with a different hook.

Neutralization data for antibodies I1 (DH270IA1) and DH429 is summarized in FIG. 9, and FIG. 10.

DH542, DH542-QSA, DH542_K3 are non-limiting examples of V3 antibodies, which can be used in combination with the antibodies of the invention. The nucleotide and amino acid sequences of the VH and VL of DH542 QSA are shown below. DH542 QSA antibody has the VH of DH542 and the VL called DH542-QSA

>DH542_HC_nt (SEQ ID NO: 465) CAGGTGCAGCTGGTGCAGTCTGGGGCTCAAATGAA GAACCCTGGGGCCTCAGTGAAGGTCTCCTGCGCGC CTTCTGGATATACCTTCACCGACTTTTACATACAT TGGTTGCGCCAGGCCCCTGGCCAGGGGCTTCAGTG GATGGGATGGATGAACCCTCAGACTGGTCGCACAA ACACTGCACGAAACTTTCAGGGGAGGGTCACCATG ACCAGGGACACGTCCATCGGCACAGCCTACATGGA GTTGAGAAGCCTGACATCTGACGACACGGCCATAT ATTACTGTACGACAGGGGGATGGATCAGTCTTTAC TATGATAGTAGTTATTACCCCAACTTTGACCACTG GGGTCAGGGAACCCTGCTCACCGTCTCCTCAG >DH542_HC_aa (SEQ ID NO: 466) QVQLVQSGAQMKNPGASVKVSCAPSGYTFTDFYIH WLRQAPGQGLQWMGWMNPQTGRTNTARNFQGRVTM TRDTSIGTAYMELRSLTSDDTAIYYCTTGGWISLY YDSSYYPNFDHWGQGTLLTVSS >DH542_LC_nt_corrected (DH542_QSA) (SEQ ID NO: 467) CAGTCTGCCCTGACTCAGCCTGCCTCCGTGTCTGG GTCTCCTGGACAGTCGATCACCATCTCCTGCACTG GAACCAAGTATGATGTTGGGAGTCATGACCTTGTC TCCTGGTACCAACAGTACCCAGGCAAAGTCCCCAA ATACATGATTTATGAAGTCAATAAACGGCCCTCAG GAGTTTCTAATCGCTTCTCTGGCTCCAAATCTGGC AACACGGCCTCCCTGACAATCTCTGGGCTCCGGGC TGAGGACGAGGCTGACTATTATTGCTGTTCATTTG GAGGGAGTGCCACCGTGGTCTGCGGCGGCGGGACC AAGGTGACCGTCCTAg >DH542_LC_aa_corrected (DH542_QSA) (SEQ ID NO: 468) QSALTQPASVSGSPGQSITISCTGTKYDVGSHDLV SWYQQYPGKVPKYMIYEVNKRPSGVSNRFSGSKSG NTASLTISGLRAEDEADYYCCSFGGSATWCGGGTK VTVL

DH542-L4 is an antibody that has a VH of DH542 and VL of DH429 (FIG. 26)

Example 8: DH540 Antibody is Described Elsewhere

DH540 antibody is described in detail in U.S. Ser. No. 62/170,558, filed Jun. 3, 2015.

Example 9: TZMbl Neutralization Assay

TZMbl neutralization assay was conducted to determine neutralization potency and breadth of different HIV-1 viral species by DH512 and mAb 10E8. FIGS. 37 and 38 show the results of neutralization against a panel of HIV isolates in the TZMbl pseudovirus neutralization assay. FIGS. 37 and 38 also show the mean IC50, IC80 and percent of isolates neutralized at different IC50 or IC80 values.

Example 10: Isolation of Additional Antibodies from the DH511 Lineage

High Throughput Native VH:VL Sequencing from Single B Cells

Additional antibodies were isolated from the individual CH0210 by high-throughput sequencing of the paired human immunoglobulin heavy and light chain repertoire. See FIG. 39. For detailed methods, see DeKosky et al. Nature Biotechnology, 31, 166-169 (2013), and DeKosky et al. Nature Medicine, 21, 86-91 (2015). Briefly B cells were isolated from PBMCs via negative depletion. The heavy and light chain transcripts were co-localized on RNA binding beads, and then physically tied together using overlap extension RT-PCR. The paired VH:VL amplicons were then used to generate 3 libraries for sequencing: a heavy chain database, a light chain database, and a paired database. The necessity for three databases stems from the fact that MiSeq currently limits the forward and reverse reads to ˜300 bp each (approximate read lengths are shown below as arrows). As the heavy and light chains are both longer than 300 nucleotides, the full length heavy and full length light chains were sequenced separately and the paired database was used as a key to stitch the heavy and light chains together by matching unique CDR3 sequences.

F(ab)2 fragments were prepared from total serum IgG and subjected to antigen-affinity chromatography using the MPER peptide. Proteins in the elution and flow-through were denatured and reduced, alkylated, trypsin-digested and analyzed by high resolution LC-MS/MS. Spectra were interpreted with the heavy chain database obtained from next-generation sequencing, and peptides uniquely associated with a single CDR (“informative peptides”) were used to identify full-length VH sequences. Clonotypes are defined as VH sequences having the same germline V and J and at least 85% aa identity in the CDRH3. To identify the MPER-binding antibodies, the focus was on the clonotypes that contain the identified CDR3 peptides and were highly enriched in the elution. This identified three clonotypes: 137, 335 and 195. All three clonotypes use the same VDJ combination (VH3-15, DH3-3, and JH6), which was also utilized by the DH511 series MPER lineages.

Based on VH sequences it was apparent that the antibodies pulled out by the paired VH:VL sequencing technology were members of the DH511 clonal lineage. Therefore, all of the antibodies are named starting with DH511. The numbers after the underscore correspond to the cluster names that were designated by the VH:VL sequencing. Antibodies were clustered by 96% nucleotide identity in the CDR3.

The above analysis identified additional MPER antibodies listed below:

PTID Ab ID H ID K/L ID 704-01-021-0 DH511_1a_4A DH511_1AVH_4A DH511_1AVK 704-01-021-0 DH511_1b_4A DH511_1BVH_4A DH511_1AVK 704-01-021-0 DH511_2a_4A DH511_2AVH_4A DH511_2AVK 704-01-021-0 DH511_2b_4A DH511_2BVH 4A DH511_2AVK 704-01-021-0 DH511_2c_4A DH511_2CVH_4A DH511_2AVK 704-01-021-0 DH511_3a 4A DH511_3AVH_4A DH511_3AVK 704-01-021-0 DH511_3b_4A DH511_3AVH_4A DH511_3BVK 704-01-021-0 DH511_3c_4A DH511_3AVH_4A DH511_3CVK 704-01-021-0 DH511_4a_4A DH511_4AVH_4A DH511_4A4CVK 704-01-021-0 DH511_4a_4bK_4A DH511_4AVH_4A DH511_4BVK 704-01-021-0 DH511_4b_4aK_4A DH511_4BVH_4A DH511_4A4CVK 704-01-021-0 DH511_4b_4A DH511_4BVH 4A DH511_4BVK 704-01-021-0 DH511_4c_4A DH511_4CVH_4A DH511_4A4CVK 704-01-021-0 DH511_4c_4bK_4A DH511_4CVH_4A DH511_4BVK 704-01-021-0 DH511_5a_4A DH511_5AVH_4A DH511_5AVK 704-01-021-0 DH511_5b_4A DH511_5BVH_4A DH511_5AVK

VH and VL genes were selected and made in linear cassettes (essentially as described in Liao H X et al. J. Virol. Methods 158: 171-9, 2009, see for example FIG. 1, Section 3.3) to produce recombinant monoclonal antibodies by transient transfection in 293T cells. See also Example 1 for variations in the backbone.

Example 11: Heavy and Light Chain Chimeric Antibodies; Antibodies with Changes in the Amino Acids of the VH Chain

This example describes chimeric antibodies comprising non-natural VH and VL chain pairs. Naturally occurring VH or VL chain are combined in non-natural pairs as described in FIG. 55, chimeras 1-91.

Chimeras 1-91 were recombinantly expressed and their neutralization profile was determined in the TZMB1 assay (FIG. 56). Based on neutralization data for chimeras 68-91 as shown in FIG. 56, three antibodies DH512_K2_4A (VH: H510049_4A (DH512) and VL: DH511_1AVK), DH512_K3_4A (VH: H510049_4A (DH512) and VL: DH511_2AVK) and DH512_K4_4A (VH: H510049_4A (DH512) and VL: DH511_5AVK) antibodies were produced large scale and will be tested for neutralization against a larger panel of viruses (see panels for DU512).

The invention contemplates antibodies which comprise amino acid changes, or combination of such changes, in the VH chains of antibodies form the DH511 lineage. Non-limiting examples of antibodies with mutations are provided in FIGS. 30-33, or any combination thereof. Most mutations are to changes to W, but can also try F, L or possibly other substitutions, e.g. without limitation I, V, A. Additional mutations include without limitation the following: T100aF; T100aL; T100aI; T100aV; T100aA; L100dW, or any combination thereof.

In some embodiment, such double mutants: T100aW-L100dF; T100aW-L100dW; T100aF-L100dF; T100aL-L100dF; T100aL-L100dW.

Neutralization data for a subset of these antibodies is provided in FIG. 34. The data show that some of the mutations abrogate neutralization while others enhance potency. One candidate, DH512 L100dF_4A, is more potent than 10E8 and has similar potency to DH512_K3.

In some embodiments, L100d could be changed to Trp.

Data in FIGS. 34 and 80 show that single mutant L100dF, and single mutant T100aW have improved neutralization. These single mutants will be tested against a panel of additional viruses (see panel for DH512, DH512_K3).

Contemplated are also combination mutations, for example but not limited combination T100aW with L100dF, combination L100dW with T100aW.

Mutated VH chain as contemplated above could be combined with VH chain from DH512, or with VH chain from DH512_K3 (DH511_2AVK).

Example 12: Shared Memory and Plasma Repertoires of HIV-1 Neutralizing Antibodies

Shared Memory and Plasma Repertoires of HIV-1 Neutralizing Antibodies

Understanding the relationship of the memory B cell and plasma immunoglobulin repertoires of HIV-1-infected individuals who develop broadly neutralizing antibodies (bnAbs) is important, since plasma antibody responses are required to achieve maximum protection from infectious agents. Using HIV-1 envelope gp41 membrane-proximal external region (MPER)-specific memory B cell sorting and next-generation sequencing, coupled with mass spectrometry analysis of plasma antibodies, we probed the memory B cell and plasma antibody repertoires of an HIV-1-infected donor with a plasma bnAb signature that mapped to Env gp41 distal MPER. We found potent IgG bnAbs from the same B cell clonal lineage in memory B cells and plasma that neutralized 99% of HIV-1 isolates. Structural analysis demonstrated clonal lineage antibodies from memory B cells and plasma both recognized the envelope gp41 epitope identically in an alpha helical conformation. Thus, a major source of potentially protective plasma HIV-1 bnAbs is the memory B cell pool.

Introduction

Inducing broadly reactive neutralizing antibodies (bnAbs) is critical for developing a protective HIV-1 vaccine. Some of the broadest bnAbs isolated are to the envelope gp41 membrane proximal external region (MPER), with two of these, 10E8 and 4E10, the most broad (1, 2). Monoclonal antibody (mAb) 4E10, while extremely broad in neutralization breadth, is not potent, and is highly polyreactive with many non-HIV-1 proteins and autoreactive with the human protein splicing factor 3b subunit 3 (SF3B3) (3) as well as with lipids (4). In contrast, mAb 10E8 is not as polyreactive as 4E10, and is both more broad and potent (1), although it does have a degree of lipid reactivity (5) and is autoreactive with the host protein family of sequence similarity 84 member A (FAM84A) (6).

To date, all HIV-1 broadly neutralizing antibodies have been isolated from memory B cells, either with clonal memory B cell cultures or using fluorophore-labeled Env and flow cytometry cell sorting. However, most correlates of protection for infectious agents with successful vaccines are the levels of plasma neutralizing antibodies. Moreover, the correlate of decreased transmission risk in the only HIV-1 vaccine trial to demonstrate a degree of efficacy was plasma antibodies to the second variable loop (V2) region (7).

In HIV-1 infection, 60% of HIV-1-specific antibodies derive from abnormal B cell subsets, that are either activated or exhausted and express Fc receptor-like-4 (FcRL4) (8, 9). However, many of the antibodies reflected in HIV-1 memory B cells are not expressed in plasma (8). Similarly, many of the memory B cell specificities of antibodies in other settings are also not represented in plasma (10-12). Thus, it is not known if envelope-reactive memory B cells with bnAb B cell receptors are a major source of plasma broad neutralizing activity.

Here we have isolated memory B cell and plasma broad and potent envelope gp41 bnAbs from an African donor and demonstrated broad and potent plasma gp41 bnAbs to be in the same B cell clonal lineage as those isolated from memory B cells. Chimeric antibodies consisting of memory bnAb V_(H) and plasma bnAb V_(L) as well as engineering memory bnAb heavy chain complementary determining regions yield antibodies with greater potency than naturally paired antibodies. Thus, the class-switched memory B cell pool contributes to plasma bnAbs.

Results

Isolation of Memory B Cell gp41 Neutralizing Antibodies

Neutralization-based epitope prediction analysis revealed that plasma from HIV-1 clade C-infected individual CH0210 contained C-terminal MPER bnAb activity (13) (FIG. 62). Six clonally-related mAbs, designated DH511.1-DH511.6, were isolated by antigen-specific single memory B cell sorting using MPER peptide fluorophore-labeled probes (14) (FIG. 59a, 59b , and Supplementary Table 1). The DH511 B cell clonal lineage was distinguished by HCDR3 loops of 24 amino acids in DH511.1, DH511.3, and DH511.6, while DH511.2, DH511.4, and DH511.5 antibodies had a one amino acid deletion in the HCDR3, resulting in a length of 23 amino acids (Supplementary Table 1). V_(H) and V_(L) somatic mutation rates were 15-22% and 14-18%, respectively. The DH511 clonal lineage was derived from the same heavy-chain germ line gene as previously isolated gp41 neutralizing antibody 10E8 (V_(H)3-15), but utilized a different V_(L) germ line gene (DH511: V_(K)1-39, 10E8: V_(L)3-19) (1) (Supplementary Table 1). Antibody DH517, derived from a second clonal lineage arising from the same donor, was similarly isolated. DH517 utilized V_(H) 4-34 and V_(L)3-19 germ line genes, was 22.8% and 14.3% mutated, respectively, and had a long HCDR3 comprised of 24 amino acids.

DH511.1-DH511.6 and DH517 mAbs were assessed for neutralization breadth and potency against a panel of 30 cross-clade HIV-1 isolates. All six DH511 clonal members neutralized 30 of 30 isolates tested with median 50% inhibitory concentrations (IC50) ranging from 0.7 to 4.2 μg/ml (Supplementary Table 2a). DH517 had less breadth than DH511 clone antibodies, neutralizing 15 of 30 isolates with a median IC₅₀ of 5.7 μg/ml (Supplementary Table 2a). The most potent DH511 clone bnAb (DH511.2) in a large cross-clade panel of 199 geographically and genetically diverse HIV-1 Env pseudoviruses, neutralized 197/199 (99%) viruses but was less potent than 10E8 (195/200, 98%) (median IC50, DH511.2=1.1 μg/ml and 10E8=0.4 μg/ml) (FIG. 59c, 59d , and Supplementary Table 3). Neutralization curves revealed that DH511.2 achieved >99% maximal neutralization for 93% of the isolates (FIG. 59e ), and showed similar potency and breadth of neutralization against a second panel of 200 clade C primary HIV-1 isolates (Supplementary Table 4).

Isolation of Plasma Gp41 Neutralizing Antibodies

We next analyzed the MPER-specific plasma antibody repertoire from donor CH0210 using an independent proteomics-based approach for the identification and semi-quantitative determination of antigen-specific antibodies in human serum (15, 16). MPER-specific antibodies were isolated from a 2 ml plasma sample by affinity chromatography, processed for proteomics (10) and subjected to liquid chromatography high-resolution tandem mass spectrometry (LC-MS/MS) analysis. For peptide identification, a donor-specific VH database comprising 98,413 unique high quality sequences was derived from a natively paired VH:VL repertoire from 845,000 peripheral single B cells from total PBMCs (isolated using MACS negative selection: CD2⁻CD14⁻CD16⁻CD43⁻CD235a⁻) (17-19). These V_(H) sequences were then clustered into 4,428 clonotypes, using a cut-off of ≥85% amino acid identity in the HCDR3 region.

Using stringent data filtering protocols (10), high confidence peptide-spectrum matches (PSMs) from HCDR3 peptides were identified and their respective LC peak intensities were used for relative quantification. As we have shown previously, an estimated >80% of all HCDR3 peptides within a sample are typically identified in this manner (detection limit approximately 0.4 ng/ml), and peak intensities correlate well with absolute peptide concentrations (10, 15). Plasma Ig clonotypes were defined as VH sequences having the same germline V and J and 85% aa identity in the HCDR3.

We found that the MPER-specific plasma antibody repertoire consisted of 10 clonotypes, three of which used the same VDJ combination (VH3-15, DH3-3, JH6) as the DH511 clonal lineage (FIG. 63). Clonotype IV comprised 95% of the total intensity of HCDR3 peptides detected in the MPER-specific antibody repertoire (i.e. in antibodies eluted following affinity chromatography with immobilized MPR.03 peptide); we noted that detection of HCDR1 and HCDR2 peptides unique to Clonotype IV provided further unambiguous support for the prevalence of these antibodies in the CH0210 plasma (FIG. 59f ). Clonotype II, which included antibodies DH511.2, DH511.4 and DH511.5 isolated by single-cell sorting, and Clonotype III were detected at 4% and 1% relative abundancy, respectively (FIG. 59f ). All three HCDR3 clonotypes utilized the same VDJ genes (V_(H)3-15, D_(H)3-3 and JH6), displayed similar HCDR3 lengths of 23-24 amino acids and VH gene mutation rates of 15-20% (Supplementary Table 6). Whereas 11 VH DH511 clonal lineage members were found by mass spectrometry (Supplementary Table 6, FIG. 64), the phylogram was collapsed to represent the most prevalent members (FIG. 59f ). It is noteworthy that Clonotype I (FIG. 59g ), that includes DH511.1, DH511.3 and DH511.6, was isolated by memory B cell sorting but was not detected in the plasma; we validated that recombinant DH511.1, DH511.3 and DH511.6 antibodies were readily detectable by mass spectrometry, indicating that their absence from the CH0210 plasma was not a technical artifact.

Using the proteomically identified HCDR3 sequences, we searched the native VH:VL sequence database comprising 200,000 heavy-light chain pairs from single B cells to determine the respective full-length light-chain sequence belonging to each clonotype (Supplementary Table 6). For clonotypes in which multiple VH:VL somatic variants were detected, only the two most frequent variants, as quantified by the number of sequencing reads, were selected for expression and characterization (Supplementary Table 6). The light-chains belonging to these three clonotypes all shared the same V- and J-gene identity (IGKV1-39, IGKJ2) as the light-chains of the DH511 clonal lineage isolated by memory B cell single-cell sorting. Six plasma mAbs belonging to the DH511 clonal lineage (designated DH511.7P-DH511.12P), showed potent tier 2 neutralizing activity against a panel of four HIV-1 isolates (Supplementary Table 7), with mAbs DH511.11P and DH511.12P demonstrating the most potent neutralizing activity. DH511.11P and DH511.12P were selected for further characterization of their neutralization breadth and potency against a panel of 203 cross-clade isolates and had slightly more breadth (99.5% of isolates tested) and greater potency than memory B cell-derived DH511.2 but were less potent than 10E8 (median IC₅₀: 0.7 μg/ml for DH511.11P and DH511.12P versus 0.4 μg/ml for 10E8) (Supplementary Table 8).

Structural Analysis of DH511 Lineage Antibodies

We used a panel of alanine substituted MPER peptides that span gp41 residues 671-683 (Supplementary Table 9) to define the epitopes of DH511.1-DH511.12P by enzyme linked immunosorbent assay (ELISA). Similar to the epitopes of 4E10 and 10E8 (1), DH511.1-DH511.12P binding was sensitive to alanine mutations at Asn671_(gp41) and Trp672_(gp41), but unlike 4E10 and 10E8, was also sensitive to Asp674Ala_(gp41), and to a lesser extent Leu679Ala_(gp41) mutations (FIG. 63). Assessment of the neutralization activity of DH511.1-DH511.12P (not DH511.7-DH511.10) mAbs against clade C COT6.15 Env pseudoviruses bearing alanine substitutions across the MPER (20, 21) (Supplementary Table 10) demonstrated sensitivity of neutralization to Env mutations of Phe673Ala_(gp41), Asp674Ala_(gp41), and Asp674Ser_(gp41), with the most prominent resistance observed against the Trp672Ala_(gp41) mutant virus (Supplementary Table 11). These data demonstrated that the epitope recognized by DH511 lineage antibodies was similar to but distinct with those of gp41 bnAbs 4E10 and 10E8, requiring the aspartic acid at position 674 for binding and neutralization.

Crystal structures of the antigen-binding fragments (Fab) of the DH511.1 antibody in complex with a peptide spanning the full gp41 MPER (residues 656-683) and of the DH511.2 antibody in complex with gp41 peptides spanning residues 662-683 and 670-683 were determined to 2.7 Å, 2.6 Å and 2.2 Å resolution, respectively (FIG. 60, FIG. 62 and Supplementary Tables 12 and 13). Both DH511.1 and DH511.2 recognized an alpha-helical conformation of the distal portion of the gp41 MPER (residues 671-683) (FIG. 60a ), similar to the conformation recognized by neutralizing antibodies 10E8 and 4E10 (FIG. 61b ). C□ RMSDs for this region of gp41 across all four antibody-bound structures did not exceed 0.46 Å. Ordered electron density for the bound peptides was also observed upstream of the distal gp41 MPER helix. In the case of DH511.1, an additional □-helix was present between residues 656-661, followed by an extended conformation between residues 662-670 (FIG. 60a ). DH511.2-bound MPER also adopted an extended conformation between residues 662-670, upstream of the distal helix, with the highest degree of overall structural homology to DH511.1-bound MPER occurring between gp41 residues 668-683 (C□ RMSD=0.39 Å) (FIG. 60a ). Interactions between DH511.1 and DH511.2 and gp41 MPER were mediated exclusively by their heavy chains, with VH3-15-encoded regions accounting for 45-50% of the antibody contact interface with gp41, and HCDR3 loops accounting for 50% or more of the remaining interface (FIGS. 60b and 61c , Supplementary Table 14). A total of 751.1 and 681.4 Å² interactive surface area was buried on DH511.1 and DH511.2, respectively, and 797.2 and 780.1 Å² on gp41 MPER in the two respective structures (Supplementary Table 14). The larger interface observed for the DH511.1 complex was due to the longer gp41 MPER peptide of that complex and the additional interface observed between its N-terminus and the antibody. It is likely that this additional interface is due to crystal lattice constraints, since alanine scan mutagenesis of N-terminal gp41 MPER residues did not result in reduction of antibody binding (FIG. 65). Contacts between DH511.1 and DH511.2 and gp41 MPER were highly conserved in both structures (FIG. 60c and Supplementary Tables 15-16). VH3-15-encoded residues of both DH511.1 and DH511.2 mediated interactions with gp41 residues L669, W670, N671, W672, F673, and D674, while their HCDR3 loop residues contacted gp41 residues W672, T676, L678, W679 and R683, as well as 1675 in the case of DH511.2 (FIG. 60c and Supplementary Tables 15-16). The interactions observed in the structures were consistent with alanine scan analyses that revealed reduced antibody binding upon mutation of gp41 residues 671-674 and 679 (FIG. 65). Interactions between DH511.1 and DH511.2 and main-chain atoms of gp41, which would be difficult to detect in alanine scan analyses, were also observed, including between antibody residue N31 and the carbonyl oxygen of gp41 W670 (FIG. 60c and Supplementary Tables 15-16).

To compare atomic-level recognition of gp41 MPER by plasma-derived versus memory B-cell-derived antibodies, structural studies of the plasma-derived DH511-lineage antibodies DH511.11P and DH511.12P were undertaken in complex with gp41 MPER peptides. Crystal structures of DH511.11P and DH511.12P Fabs were determined in complex with a peptide spanning gp41 MPER residues 662-683, to 2.47 and 1.88 Å, respectively (FIG. 60c and Supplementary Tables 12 and 13). The structures revealed that both plasma derived variants recognized a conformation of the MPER similar to that recognized by DH511.1 and DH511.2, adopting an □-helix between residues 671-683 and an extended conformation upstream, between residues 662-670. The highest degree of structural homology occurred between residues 668-683. As in the case of DH511.1 and DH511.2, interactions between DH511.11P and DH511.12P and gp41 were mediated exclusively by their heavy chains (FIG. 60d and Supplementary Table 14). The plasma-derived variants recognized the very same gp41 residues as those recognized in common by DH511.1 and DH511.2, although the respective antibody residues that mediated these contacts with gp41 differed in some cases (FIG. 60b, 60d, 60e and Supplementary Tables 15-18). While contacts between HCDR1 loop residues of the DH511.11P and DH511.12P and gp41 were largely conserved relative to those of DH511.1 and DH511.2, gp41 contacts mediated by their HCDR2 loops diverged relative to those of DH511.1 and DH511.2 (FIG. 60). The substitution of DH511.1 and DH511.2 HCDR2 residue K52c with a glycine in DH511.11P and DH511.12P, led to the loss of a salt bridge mediated by K52c and gp41 residue D674—one that was replaced by an additional salt bridge mediated by conserved residue R52a (FIGS. 60b, 60d, 60e and Supplementary Tables 15-18). Examination of additional gp41-contacting residues that were unique to the plasma-derived variants revealed that unique residues of their HCDR3 loops, which differed from the DH511.1 and DH511.2 HCDR3 loops at ˜7 residue positions, mediated many of these contacts (FIG. 60c and Supplementary Tables 17-18). Despite their overall sequence divergence from DH511.1 and DH511.2, ˜26-28% in heavy chain variable regions, the structures of the DH511.11P and DH511.12P were highly homologous to those of DH511.1 and DH511.2. In sum, the plasma-derived variants examined here recognized a similar conformation of the gp41 MPER as that recognized by memory B-cell derived variants, contacted a similar set of gp41 residues, and did so through modified antibody contacts that did not significantly alter the backbone conformations of their paratopes or common epitope.

We next compared the structures of DH511 lineage antibodies to those of other antibodies that target the distal gp41 MPER (FIGS. 61a and 61b ). Since the DH511 lineage shares a common VH3-15 heavy chain precursor as the 10E8 lineage, we were especially interested in determining if a structural basis for usage of this precursor to target the MPER could be discerned. As a first step, we compared the directions of approach of DH511 lineage antibodies to the distal MPER helix, relative to those of 10E8 and 4E10. All four antibodies were oriented by superimposing residues 671-683 of their respective epitopes, and their directions of approach were defined by a line drawn from the Ca atom of epitope residue 672 to a point midway between the variable region intra-chain heavy and light chain disulfide bonds, which represented the longitudinal axis of the antibody variable regions. Pairwise comparison of the directions of approach of DH511.1 versus those of DH511.2, 10E8 and 4E10 yielded differences of 4.7°, 13.4° and 25.2°, respectively, suggesting the DH511 lineage most closely resembled 10E8 in its approach to the epitope (FIG. 61d ). While the longitudinal axes of the DH511.1 and DH511.2 variable regions and that of 10E8 were highly similar, the orientations of their heavy and light chains relative to this longitudinal axis differed more substantially—by ˜54° (FIG. 61d ). This difference resulted in a rotational shift of the gp41 footprint on 10E8 relative to the footprint on DH511 lineage antibodies (FIG. 61c ). Thus, while DH511 lineage antibodies share an identical heavy chain VH3-15 precursor as antibody 10E8, and approached gp41 MPER from similar angles, the orientations of their heavy and light chains relative to the epitope differed more substantially.

To determine if a common structural basis for VH3-15 precursor usage could nonetheless be discerned between the two lineages, we compared VH3-15-encoded gp41-contacting residues in DH511.1, DH511.2 and 10E8. Of the total number of residue interactions that exist between the VH3-15 regions of three respective antibodies and gp41 (8 for DH511.1, 10 for DH511.2, and 10 for 10E8), five common residue positions were involved interactions with gp41 in all three antibodies: 28, 31, and 33 within the HCDR1 and 52c and 53 within the HCDR2 (FIGS. 61c and 60e ). Heavy chain residues 31 and 33 are asparagine and tryptophan in all three antibodies and are un-mutated from the germ-line precursor. Residue 53 is aspartate in DH511.1 and DH511.2, as it is in the germ-line precursor, and a chemically similar glutamate in 10E8. Residue positions 28 and 52c are somatically mutated from germ-line in all three antibodies, to disparate amino acids (FIG. 61e ). While all five residues maintain contact with gp41 in both the DH511.1 and 10E8 lineages, the rotational shift in the orientations of the heavy and light chains between the two lineages results in distinct modes of gp41 recognition (FIGS. 60b and 61e ). Yet, the five common VH3-15 encoded gp41-contacting residues in both lineages end up interacting with many of the same gp41 MPER residues, including L669, W670, N671, W672, and F673 (FIGS. 60b, 60e, and 61e ). VH3-15 germ line encoded residue W33, shown in previous studies to be required for 10E8 recognition of gp41 (1), interacts with gp41 residues W672 and F673 in both the DH511.1 and 10E8 lineages, although from a distinct spatial position in each case (FIGS. 60b and 61e ). Thus, despite a relative shift in heavy and light chain orientations, a common subset of DH511.1 and 10E8 lineage VH3-15 residues interact with the same subset of distal MPER residues. It remains to be determined if the observed differences in the heavy and light chain orientations of two lineages, relative to gp41 MPER, were determined at inception of naïve antibody recognition or if they were added during antibody development and maturation.

Origin and Development of the DH511 Clonal Lineage

A maximum likelihood phylogenetic tree was constructed from the VDJ sequences recovered from memory B cell sorting and was used to infer the unmutated common ancestor (UCA) of clone DH511 and six maturational intermediate antibodies (FIG. 59b ). A global panel of 12 HIV-1 isolates was used to assess the development of neutralization breadth in the DH511 clonal lineage. None of the isolates were neutralized by the UCA or intermediate (I) 6 antibody that was most closely related to the DH511 UCA. Antibody I2 and later members of the lineage acquired the ability to neutralize 12/12 isolates (Supplementary Table 19). DH511 clone acquisition of breadth was associated with the accumulation of somatic mutations, but neutralization potency did not directly correlate with percent VH mutation frequency. Analysis of a panel of MPER peptides and MPER peptide liposomes did not reveal constructs that bound to the UCA. Binding to the MPER peptides was acquired at the 15 stage of maturation (FIGS. 66 and 67).

Polyreactivity/Autoreactivity of the DH511 Clonal Lineage

The DH511 inferred UCA and intermediates 11-13 and 16 reacted with several autoantigens as measured by ELISA (FIGS. 68-69) and were found to exhibit polyreactivity in a protein microarray against 9,400 human proteins (3) (FIG. 68). The mature members of the lineage were not polyreactive by ELISA, although some members demonstrated polyreactivity by microarray analysis (DH511.1, DH511.5, DH511.6, and DH511.12P). All DH511 lineage members lacked reactivity by indirect immunofluorescence human epithelial (HEp-2) cell staining assay. Regarding higher affinity autoreactivity with single proteins, mature bnAb DH511.2 reacted with the E3 ubiquitin ligase STIP1 Homology and U-Box Containing Protein 1 (STUB1) while both DH511.11P and DH511.12P reacted with nuclear distribution gene C homolog (A. nidulans) (NUDC); DH511.12 also reacted with Scm-like with four MBT domains protein 1 (SFMBT1) (FIG. 68).

To characterize the lipid reactivity of the DH511 clonal lineage, we first determined propensity for lipid membrane binding/insertion of DH511.1-DH511.6 based on HCDR3 hydrophobicity. Three or more Phe or Trp amino acid residues were contained within the HCDR3 sequences of each DH511 clonal lineage member, and several members were found to have at least one Pro, with the exception of DH511.3 and DH511.6. A membrane insertion score was calculated based on the Wimley-White hydrophobicity scale, which measures the propensity of amino acids to sit at the interface of the head and tail group in a lipid bilayer. Notably, membrane insertion scores were similar between the most potent neutralizer DH511.2 and 4E10/10E8 but differed from 2F5 (Supplementary Table 21).

To further delineate the interaction of DH511 clonal members with the lipid bilayer interface, we determined cardiolipin reactivity and kinetics of binding to MPER peptide versus MPER peptide-liposome conjugates. The UCA and members of the memory B cell clonal lineage did not bind cardiolipin in ELISA (Supplementary Table 22). The binding of gp41 bnAbs 2F5 and 4E10 to gp41-lipid complex has been proposed as a sequential two-step process, in which encountering the lipid membrane takes place first, presumably to aid in docking of the antibody with the transiently exposed gp41 intermediate neutralizing epitope during the virion-host cell fusion process (4, 22, 23). Surface plasmon resonance (SPR) analysis of DH511 lineage fragments of antigen binding (Fabs) demonstrated that DH511.1-DH511.6 and intermediates I1-I5 bound the MPER peptide (NEQELLELDKWASLWNWFDITNWLWYIR (SEQ ID NO: 2)) with nanomolar affinity (Kd range: 11.1-99.9 nm), while the inferred UCA and intermediate 6 (most closely related to the UCA) did not bind (FIG. 66). Binding kinetics studies as show in FIG. 71), support the hypothesis that like 2F5 and 4E10, DH511 lineage antibodies bind in a two-step conformational change model.

To determine the impact of timing of the gp41 intermediate epitope exposure on HIV-1 neutralization (24), we compared the window of time in which bnAbs DH511.2, 10E8, and 4E10 could neutralize the tier 2 HIV-1 strain B.BG1168 after virus addition to TZM-bl cells. The lifetime of neutralization for DH511.2 (t_(1/2): 26.8±2.3 min) was the same as that for bnAbs 10E8 (t_(1/2): 25.6±2.5 min) and 4E10 (t_(1/2): 28.2±3.5 min), similar to the published half-life of fusion inhibition by the gp41 intermediate mimic T20 (20.2±0.5 min) (24). These results suggest that DH511.2 recognizes a transiently exposed intermediate state of gp41 (25).

Engineering DH511 Clonal Lineage Members for Enhanced Potency

To identify more potent variants of the DH511 clonal lineage, we generated 91 chimeric mAbs by swapping the heavy and light-chains of DH511.2 with those of DH511 lineage members derived from the plasma. Of the 91 chimeric antibodies, one variant, DH511.2_K3 (comprised of the DH511.2 heavy-chain reconstituted with the plasma light-chain of DH511.8P), showed greater potency than 10E8 (Supplementary Table 24). DH511.2_K3 neutralization data are shown in FIGS. 28 and 58.

Sixteen HCDR3 mutations of DH511.2 were made (FIGS. 30-33) to determine effect on DH511.2 potency. FIG. 34 shows neutralization data for sixteen of these antibodies. Additional mutations will be made, including combinations of mutations, from the mutations listed in FIGS. 30-31.

Discussion

We have used a combination of memory B cell sorting (26, 27) and plasma antigen-specific antibody characterization by HCDR3 mass spectrometry sequencing to simultaneously characterize class-switched memory B cell antibodies and plasma antibodies (15, 28-30). The memory B cell repertoire contains multiple specificities of antibodies reflective of an individual's immune history (30) whereas primary contributors to plasma antibodies are both long lived plasma cells as well as shorter lived plasma cells derived from terminally differentiated memory B cells in response to current antigens (16). However, evidence exists that for non-HIV-1 antigens such as influenza (11) and West Nile virus (12), not all of the memory B cell repertoire is found in plasma. Here we demonstrate that class-switched memory B cells and plasma shared the same clonal lineage members of highly broad and potent HIV-1 gp41 neutralizing antibodies.

In the case of HIV-1 antibody responses, the relationship of the memory B cell and plasma antibody pools is complicated by the damage that HIV-1 inflicts on the B cell lineage with disruption of the germinal center in the earliest stages of infection (31), and the accumulation of FcRL4+ memory B cells in chronic infection (8). Interestingly, HIV-1-specific B cell responses are enriched in the FcRL4+ memory B cell compartment and exhibit many features of premature exhaustion (8). Regarding antibodies that target the Env bnAb epitope at the CD4 binding site, it has been shown that ˜60% of this response is contained within the exhausted FcRL4+ memory B cell compartment, thus preventing their progression to plasma cells and production of secreted antibody (8, 9). In contrast, Scheid and colleagues studied antigen-specific memory B cell repertoires in HIV-1 infected individuals and found broad diversity of neutralizing antibodies (32). Moreover, analysis has demonstrated bnAb activity in plasma can predict isolation of bnAb variable heavy (V_(H)) and variable light (V_(L)) from memory B cells from the same individual (13, 33-38). Moreover, only a limited number of bnAb specificities are generally present in HIV-1-infected plasma (38, 39), and when bnAbs are isolated from memory B cells in clonal memory B cell cultures, the bnAbs are the minority of the Env specifities isolated (26, 37, 40). Thus, in spite of early damage to B cell follicles and accumulation of memory B cells with an exhaustion phenotype, HIV-1 infected individuals can make productive, albeit subdominant, bnAb responses that progress to plasma cell differentiation and secretion into blood plasma.

A critical question is whether memory B cells in HIV-1 infected individuals are differentiating into the long-lived plasma cell pool that resides in bone marrow and is responsible for long-lived plasma antibody responses (41). We have previously studied the effect of anti-retroviral treatment in HIV-1 infection on the half-lives of Env gp120 and gp41 as well as Gag antibody responses, and demonstrated whereas Env antibody half-life was short for gp120 (81 weeks) and gp41 (33 weeks), antibody half-life was longer for Gag (648 weeks). In contrast, in the same individuals, the half-life of influenza antibodies did not decay over the time studied (42). These data demonstrate that in chronic HIV-1-infection, the cells making plasma gp41 antibodies are not long-lived plasma cells.

Thus, by directly measuring the gp41 broad neutralizing repertoire in memory B cells and plasma, we have directly demonstrated the survival from immune damage of memory B cells to produce plasma broadly neutralizing antibodies. Finally, we show that blood plasma is a rich source for isolation of potent bnAbs for recombinant antibody production and for constructing chimeric memory B cell/plasma antibodies for enhancing antibody potency and breadth.

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Supplementary Materials and Methods

Donor Information

Plasma and peripheral blood mononuclear cells were collected from South African donor CH0210, chronically infected with a clade C virus for an unknown period at the time of enrollment in the Center for HIV/AIDS Vaccine Immunology (CHAVI) 001 chronic HIV-1 infection cohort (previously described in (33). Informed consent was obtained under clinical protocols approved by the Institutional Review Board of the Duke University Health System and clinical site in South Africa. The DH511 bnAb lineage was isolated from PBMC and plasma collected at 8 weeks post-study enrollment, where the viral load was 5,180 copies/ml and CD4 T cell count was unknown, at which time donor CH0210 had not initiated anti-retroviral therapy (ART).

Epitope Mapping and Neutralization-Based Epitope Prediction Analysis

Donor CH0210 plasma was screened for neutralization breadth utilizing standard experimental mapping and computational methods for epitope prediction (13, 43). Anti-MPER bnAb activity was detected using two different assays: plasma neutralization of the HIV-2/HIV-1 MPER chimeric pseudovirus C1C and plasma adsorption with MPER peptide coated magnetic beads, followed by testing of adsorbed plasmas for reduction of neutralization activity as described previously (44). An algorithm for Neutralization-based Epitope Prediction (NEP) (13, 43) was used to delineate the specificities mediating breadth against a panel of 21 diverse HIV-1 strains. The resulting linear coefficients on a scale of (0 to 1) from the computational procedure was used to predict the relative prevalence of each of the reference antibody specificities in donor CH0210 plasma.

Antigen-Specific Single Memory B Cell Sorting and Antibody Expression

As previously described (14), fluorescently-labeled MPER peptide tetramer probes were generated using biotinylated MPR. 03 peptide (KKKNEQELLELDKWASLWNWFDITNWLWYIRKKK-biotin (SEQ ID NO: 463)) (CPC Scientific Inc., San Jose, Calif.) conjugated to fluorophore-labeled streptavidins, yielding a tetramer with four MPER epitopes for surface Ig cross-linking. Eleven and a half million PBMC from donor CH0210 were stained with MPR.03-Alexa647 and MPR.03-Brilliant Violet 421 peptide tetramers and a cocktail of antibodies to identify MPER-specific memory B cells: surface IgM (FITC), surface IgD (phycoerythrin [PE]), CD3 (PE-Cy5), CD16 (Brilliant Violet 570), CD235a (PE-Cy5), and CD19 (allophycocyanin [APC]-Cy7) (BD Biosciences, San Jose, Calif.); CD14 (Brilliant Violet 605) (Invitrogen, Carlsbad, Calif.); CD27 (PE-Cy7), CD38 (APC-Alexa Fluor 700) (Beckman Coulter, Brea, Calif.), and CD10 (ECD) (Beckman Coulter, Brea, Calif.). Aqua blue vital dye (Invitrogen, Carlsbad, Calif.) was used to stain dead cells. Using a four laser FACS Aria cell sorter and FACSDiva software (BD Biosciences, San Jose, Calif.), MPR.03 double positive CD16-CD14-CD3-CD235-CD19+IgD-CD38hi memory B cells were single cell sorted into individual wells of a 96-well plate containing reverse transcription (RT) reaction buffer (5 μL of 5′ first-strand cDNA buffer, 0.5 μL of RNaseOUT [Invitrogen, Carlsbad, Calif.], 1.25 μL of dithiothreitol, 0.0625 μL Igepal CA-630 [Sigma, St. Louis, Mo.], 13.25 μL of distilled H2O [dH2O; Invitrogen, Carlsbad, Calif.]). Data were further analyzed using FlowJo software (TreeStar, Ashland, Oreg.). Plates were stored at −80° C. until PCR could be performed.

PCR Amplification and Expression of Ig Genes

Immunoglobulin genes were amplified from RNA of isolated cells by reverse transcription-polymerase chain reaction (RT-PCR). For RT, 10 mM dNTPs (New England Biolabs, Ipswich, Mass.), 3 μl random hexamers at 150 ng/ml (GeneLink, Hawthorne, N.Y.), and 1 μl SuperScript® III (Invitrogen, Carlsbad, Calif.) were added to each well and subjected to thermocycling under the following conditions: 42° C. for 10 minutes, 25° C. for 10 minutes, 50° C. for 60 minutes and 94° C. for 5 minutes. IgH, Igκ, and Igλ variable region genes were separately amplified from the cDNA by nested PCR, using AmpliTaq Gold® 360 Mastermix (Invitrogen, Carlsbad, Calif.), heavy-chain (45) and light-chain gene-specific primers as previously described (46). PCR amplicons were purified and sequenced, and V_(H)DJ_(H) and VOL genes, mutation frequencies, and CDR3 lengths were determined using the Clonanalyst software (47). Clonal relatedness and inference of the unmutated common ancestor (UCA) and intermediate antibodies were determined by computational methods as described in (26, 40, 48). Maximum likelihood phylogenetic trees were constructed from V(D)J sequences using the Phylogeny Inference Package (PHYLIP) (version 3.69; (49). Transient small-scale expression of antibodies was achieved by overlapping PCR assembly of variable heavy and light-chain gene pairs into IgH, Igκ, and Igλ linear expression cassettes for production of full length IgG1 mAbs by transfection into 293T cells as described previously (46). Supernatants were screened for HIV-1 Env binding by ELISA and neutralization activity in TZM-bl cells. For large scale antibody production, antibody variable heavy-chain and light-chain genes were de novo synthesized (GenScript, Township, N.J.), cloned into pcDNA3.1 expression vectors containing the constant regions of IgG1 (46), and co-transfected at equal ratios in Expi 293i cells using ExpiFectamine 293 transfection reagents (Thermo Fischer Scientific, Waltham, Mass.) according to the manufacturer's instructions. Culture supernatants were harvested and concentrated after 4-5 days incubation at 37° C. and 8% CO₂, followed by affinity purification by protein A column (Pierce, Thermo Fisher Scientific, Waltham, Mass.). Antibody purity was evaluated by SDS-Page and Coomassie Blue staining for heavy and light-chains of the appropriate size.

ELISA Assays

Binding of transiently transfected supernatants and mAbs to HIV-1 Env proteins and peptides was detected by enzyme-linked immunosorbent assay (ELISA). High-binding 384-well plates (Corning, Oneonta, N.Y.) were coated overnight at 4° C. or for 2 hours at room temperature with 2 μg/ml HIV-1 protein or streptavidin (for detection of binding to biotinylated peptides) in 0.1 M sodium bicarbonate (Sigma Aldrich, St. Louis, Mo.). Plates were blocked for 1 hour at room temperature with assay diluent comprised of phosphate buffered saline (PBS), 4% (weight/volume) whey protein (BiPro USA, Prairie, Minn.), 15% normal goat serum (Invitrogen, Carlsbad, Calif.), 0.5% Tween 20, and 0.05% sodium azide (Sigma Aldrich, St. Louis, Mo.), followed by a 1 hour incubation with antibody at a starting concentration of 100 μg/ml, serially diluted 3-fold. Horseradish peroxidase-conjugated goat anti-human IgG Fc antibody (Jackson ImmunoResearch Laboratories, West Grove, Pa.) was added to each well and incubated for 1 hour, after which plates were washed with PBS/0.1% Tween 20 and developed with SureBlue Reserve TMB One Component Microwell Peroxidase Substrate for 15 minutes (KPL, Gaithersburg, Md.). Development was stopped with 0.1 M HCl, and plates were read at 450 nm. Experiments were performed in duplicate, and results were reported as logarithm area under the curve (Log AUC). For epitope mapping, purified mAbs were screened as listed above against a panel of MPR.03 alanine scanned peptides. Epitope positions were defined by MPR.03 alanine scan mutations that reduced the Log AUC by >50% compared to the wild-type peptide.

Neutralization Assays

Neutralization assays were performed using HIV-1 Env pseudoviruses to infect TZM-bl cells as previously described (50, 51). A five-parameter hill slope equation was used to fit neutralization curves by non-linear regression and for determination of maximum percent inhibition (MPI) values. Titers were calculated as 50% or 80% inhibitory concentrations (IC₅₀ and IC₈₀) and reported as the concentration of antibody causing a 50% or 80% reduction in relative luminescence units compared to virus control wells. Mapping of the MPER residues critical for neutralization was performed using a panel of alanine scanned COT6.15 Env pseudoviruses as described previously (20, 21).

Poly/Autoreactivity Analysis

Antibody binding to a panel of nine autoantigens, including Sjogren's syndrome antigen (SSA), SSB, Smith antigen (Sm), ribonucleoprotein (RNP), scleroderma 70 (Scl-70), Jo-1, double-stranded DNA (dsDNA), centromere B (Cent B), and histone, was quantified by ELISA. Anti-cardiolipin reactivity was measured using the QUANTA Lite ACA IgG III ELISA kit (Nova Diagnostics, San Diego, Calif.) per the manufacturer's instructions as previously described (52). Antibodies were assayed for reactivity to the human epithelial cell line (HEp-2) by indirect immunofluorescence staining using the IFA ANA/Hep-2 Test System (Zeus Scientific, Somerville, N.J.) per the manufacturer's protocol. Antibodies were diluted to 50 μg/ml and 25 μg/ml and scored negative or positive (1+ to 4+) at each dilution. Antibodies were also screened for binding to a panel of >9,400 human proteins using a Protoarray microarray (Invitrogen, Carlsbad, Calif.) according to the manufacturer's instructions and as described in (6). Briefly, the array was blocked and incubated on ice with 2 μg/ml HIV-1 antibody or the isotype control antibody, human myeloma protein, 151K (Southern Biotech, Birmingham, Ala.) for 90 minutes. Antibody binding was detected with 1 μg/ml anti-human IgG-Alexa-647 secondary antibody (Invitrogen). Arrays were scanned using a GenePix 4000B scanner (Molecular Devices, Sunnyvale, Calif.) at a wavelength of 635 nm, 10 μm resolution, using 100% power and 650 gain. The fluorescence intensity of antibody binding was measured with the GenePix Pro 5.0 program (Molecular Devices, Sunnyvale, Calif.).

Surface Plasmon Resonance Affinity and Kinetics Measurements

Surface plasmon resonance analysis was performed on a Biacore 3000 instrument (GE Healthcare, Little Chalfont, UK) at 25° C. and data analyzed using the BIAevaluation 4.1 software (BIAcore) as described previously (Alam et al. JI 2007). To determine the affinity, association and dissociation rate constants of the DH511 clonal lineage to MPER, biotinylated MPR.03 peptide was coated on streptavidin sensors at a density of 58 response units (RUs). DH511 lineage Fabs were injected over flow cells at increasing concentrations at a flow and minute dissociation steps. Curves were blank surface and CH58 Fab analyte subtracted. Peptide-liposome conjugates were generated with MPER656.1-GTH1 peptides using an extrusion method (4) and analyzed for binding in a two-step encounter docking model as described previously (4).

Time Course of DH511.2 Neutralization

The time course of DH511.2 neutralization was determined using a post-attachment HIV-1 pseudotyped virus neutralization assay described previously (53). Inhibitory concentrations of DH511.2, 10E8, and 4E10 mAb were added to TZM-bl cells incubated with B.BG1168 virus at different time intervals after infection. Infectivity was measured in relative light units (RLUs).

High-Throughput Paired VH:VL Sequencing of Immunoglobulin Transcripts

Material & reagents. Protein G Plus agarose, NeutrAvidin agarose, immobilized pepsin resin and Hypersep SpinTip C18 columns (C18-SpinTips) were acquired from Pierce (Thermo Fisher Scientific, Rockford, Ill.). TRIS hydrocholoride (Tris-HCl), ammonium bicarbonate (NH4HCO3), 2,2,2-trifluoroethanol (TFE), dithiothrietol (DTT), and iodoacetamide (IAM) were obtained from Sigma-Aldrich (St. Louis, Mo.). LC-MS grade water, acetonitrile (ACN), and formic acid were purchased from EMD (Billerica, Mass.).

Isolation of memory B cells. Frozen PBMCs (10 million cells in 1 mL) were thawed at 37° C., resuspended in 50 mL of RPMI 1640 (Lonza) supplemented with 10% Fetal Bovine Serum, lx non-essential amino acids, lx sodium pyruvate, lx glutamine, lx penicillin/streptomycin, and 20 U/mL DNAse I, and recovered via centrifugation (300 g for 10 min at 20° C.). The cells were then resuspended in 4 mL of RPMI and allowed to recover at 37° C. for 30 min. The cells were diluted with 10 mL of cold MACS buffer (PBS supplemented with 0.5% BSA and 2 mM EDTA), collected by centrifugation (300 g for 10 min at 4° C.), and depleted of non-B cells using the Human Memory B Cell Isolation Kit with an LD column (Miltenyi Biotec) as per the manufacturer's instructions. This yielded 400,000-500,000 B cells per vial.

Amplification of the paired VH:VL repertoire. The paired VH and VL sequences were then determined using a custom designed axisymmetric flow focusing device (19) that is comprised of three concentric tubes. Total B cells were suspended in 6 mL of cold PBS and passed through the innermost tube at a rate of 0.5 mL/min. Oligo d(T)₂₅ magnetic beads (1 μm diameter at a concentration of 45 μL beads/mL solution; NEB) were washed, subjected to focused ultrasonication (Covaris) to dissociate any aggregates, resuspended in 6 mL of lysis buffer (100 mM Tris-HCl pH 7.5, 500 mM LiCl, 10 mM EDTA, 1% Lithium dodecyl sulfate (LiDS), 5 mM DTT), and passed through the middle tube at a rate of 0.5 mL/min. The outer tubing contained an oil phase (mineral oil containing 4.5% Span-80, 0.4% Tween-80, and 0.05% Triton X-100; Sigma-Aldrich) flowing at 3 mL/min. The cells, beads, and lysis buffer were emulsified as they passed through a custom designed 120 μm diameter orifice, and were subsequently collected in 2 mL microcentrifuge tubes. Each tube was inverted several times, incubated at 20° C. for 3 minutes, and then placed on ice. Following the collection phase, emulsions were pooled into 50 mL conicals, and centrifuged (4,000 g for 5 min at 4° C.). The mineral oil (upper phase) was decanted, and the emulsions (bottom phase) were broken with water-saturated cold diethyl ether (Fischer). Magnetic beads were recovered following a second centrifugation step (4,000 g for 5 min at 4° C.) and resuspended in 1 mL of cold Buffer 1 (100 mM Tris pH 7.5, 500 mM LiCl, 10 mM EDTA, 1% LiDS, 5 mM DTT). The beads were then serially pelleted using a magnetic rack, and washed with the following buffers: 1 mL lysis buffer, 1 mL Buffer 1, and 0.5 mL Buffer 2 (20 mM Tris pH 7.5, 50 mM KCl, 3 mM MgCl). The beads were split into two aliquots, and each was then pelleted one final time and resuspended in an RT-PCR mixture (19) containing VH and VL Framework Region 1 (FR1) linkage primers or VH and VL leader peptide (LP) linkage primers (Supplementary Tables 28 and 29). The RT-PCR mixtures were then added dropwise to 9 mL of chilled oil phase in an IKA dispersing tube (DT-20, VWR) and emulsified using an emulsion dispersing apparatus (Ultra-Turrax® Tube Drive; IKA) for 5 min. The emulsions were aliquoted into 96-well PCR plates (100 uL/well), and subjected to RT-PCR under the following conditions: 30 min at 55° C. followed by 2 min at 94° C.; 4 cycles of 94° C. for 30 s, 50° C. for 30 s, 72° C. for 2 min; 4 cycles of 94° C. for 30 s, 55° C. for 30 s, 72° C. for 2 min; 32 cycles of 94° C. for 30 s, 60° C. for 30 s, 72° C. for 2 min; 72° C. for 7 min; held at 4° C.

Following RT-PCR, the emulsions were collected in 2 mL microcentrifuge tubes and centrifuged (16000 g for 10 min at 20° C.). The mineral oil (upper phase) was decanted, and water-saturated ether was used to break the emulsions. The aqueous phase (containing the DNA) was extracted three times by sequentially adding ether, centrifuging the samples (16000 g for 30 s at 20° C.), and removing the upper ether phase. Trace amounts of ether were removed using a SpeedVac for 30 min at 20° C. The DNA amplicons were purified using a silica spin column (Zymo-Spin™ I, Zymo Research) according to the manufacturer's instructions, and eluted in 40 μL H₂O. The two samples were then amplified through a nested PCR (see Supplementary Table 30 for primers) using Platinum Taq (Life Technologies) under the following conditions: (FR1 primer derived sample) 2 min at 94° C., 32 cycles of 94° C. for 30 s, 62° C. for 30 s, 72° C. for 20 s; 72° C. for 7 min; held at 4° C.; (LP primer derived sample) 2 min at 94° C., 27 cycles of 94° C. for 30 s, 62° C. for 30 s, 72° C. for 20 s; 72° C. for 7 min; held at 4° C. The amplicons, approximately 850 bp in length, were gel purified from 1% agarose using a gel extraction kit (Zymo Research) according to the manufacturer's instructions, and eluted in 20 μL H₂O.

To determine the full length VH and VL reads for antibody expression studies, the paired amplicon was subjected to an additional PCR using NEBNext high fidelity polymerase (NEB) to specifically amplify the full VH chain and the full VL chain separately in addition to the paired chains (Note: the paired reads sequence the entire J- and D-regions, and the fragment of the V regions spanning FR2 to CDR3). Each sample was split into 5 reactions and subjected to the following PCR conditions: 30 s at 98° C., X cycles of 98° C. for 10 s, 62° C. for 30 s, 72° C. for Y s; 72° C. for 7 min; held at 4° C. (See Supplementary Table 31 for the PCR conditions and Supplementary Table 32 for the primer sequences). Finally, these sequences were amplified one final time with TSBC compatible barcoding primers following the protocol shown in Supplementary Table 33, gel purified from 1% agarose using a gel purification kit according to manufacturer's instructions, and submitted for paired-end Illumina NGS.

Bioinformatic analysis of NGS data. Raw 2×300 MiSeq reads were quality filtered (minimum Phred score of 20 over half of the nucleotide sequence) and submitted to MiXCR (54) for CDR3 identification and gene annotation. Productive VH and VL reads were paired by Illumina MiSeq ID using a custom python script. Full length VH and VL reads were stitched together using FLAsH (55) and then quality filtered. Full length VH and VL constructs were designed by matching the paired CDRH3:CDRL3 nucleotide sequences to the respective CDR3 in the full length VH and VL libraries.

Sample preparation & LC-MS/MS analysis. Serum IgG from donor 0210 was purified by Protein G Plus agarose affinity chromatography, and F(ab′)2 fragments were generated by digestion with immobilized pepsin. Antigen-specific F(ab′)2 was isolated by affinity chromatography with the biotinylated MPER peptide coupled to NeutrAvidin agarose and eluted in 100 mM glycine pH 2.7. The collected fractions were neutralized and the protein containing fractions were pooled and prepared for LC-MS/MS as described previously (10). Briefly, protein samples were concentrated and resuspended in 50% (v/v) TFE, 50 mM NH4HCO3 and 2.5 mM DTT and incubated at 55° C. for 45 min. The reduced samples were then alkylated with IAM in the dark, at room temperature for 30 min. The reaction was quenched by addition of DTT and the samples were diluted to 5% TFE and digested with trypsin (trypsin/protein ration of 1:75 at 37° C. for 5 h). The digestion was stopped by addition of formic acid to 1% (v/v). The samples were then concentrated by SpeedVac, resuspended in 5% ACN, 0.1% formic acid and the peptides were washed on C18-SpinTips according to the manufacturer's protocol. Subsequently, the peptides were separated by reverse phase chromatography (Dionex UltiMate 3000 RSLCnano system with Dionex Acclaim PepMapRSLC C18 column, Thermo Scientific) and analyzed on-line by nano-ESI tandem MS on an Orbitrap Velos Pro (Thermo Scientific). MS1 scans were collected in the orbitrap at 60,000 resolution and ions with >+1 charge were fragmented by CID with up to 20 MS2 spectra collected per MS1.

Computational interpretation of peptide mass spectra. Full length VH and VL sequencing data (see above) was submitted to the IMGT/HighV-Quest Tool (56) for annotation and unique full length VH sequences were clustered into clonotypes according to their CDRH3 sequences with a cut-off of 85% identity as described previously (29). The sample-specific target protein sequence database was constructed from the full-length VH and VL sequences mentioned above (≥2 reads), Ensembl human protein-coding sequences and common contaminants (maxquant.org). The spectra were then searched against this database using the SEQUEST (Proteome Discoverer 1.4, Thermo Scientific) with previously described settings (15). The resulting PSMs were filtered with Percolator (Proteome Discoverer 1.4) to control false discovery rates (FDR) to <1% and the average mass deviation (AMD) was calculated for all high-confidence PSMs and peptides with an AMD of <1.5 ppm were kept for the final dataset. Informative peptides, as defined previously (15), were grouped by their CDRH1, 2 or 3 association and for each group the abundances of the corresponding clonotypes were determined by the sum of the extracted-ion chromatograms of the respective precursor ions.

Crystallization, Structure Determination, and Structural Analysis.

Purified DH511.1 and DH511.2 fragments of antigen binding (Fabs) were set up in crystallization trials in complex with a panel of gp41 MPER peptides. For each complex, 576 initial conditions from commercially available screens (Hampton Research, Rigaku) were set up as vapor diffusion sitting drops robotically (TTP Labtech). Crystals of DH511 Fab in complex with gp41 MPER peptide 656-683 were obtained in a condition composed of 30% PEG 1500, while those of DH511.2 Fab in complex with peptides MPR.03.DN4 and MPR.03.DN14, were obtained in 30% PEG 1500, 10% Isopropanol, 0.1 M CaCl₂, 0.1 M Imidazole pH 6.5 and in 20% PEG 8000, 10% PEG 400, 0.5 M NaCl, 0.1 M C₂H₃NaO₂ pH 5.5, respectively. Crystal hits were hand optimized and X-ray diffraction data extended to 2.8, 2.65, and 2.2 Å, respectively. Data was processed with HKL-2000 (57) and structures were solved by molecular replacement using the DH514 Fab unliganded structure as a search model in Phaser (58). The structures were refined to R_(crystal)/R_(free) of 21.28/25.57, 25.61/28.99, and 19.03/22.63%, respectively, using Phenix (59) combined with iterative model building in Coot (60). Interactive surfaces were determined using Pisa (61) and structural alignments using LSQKAB (62). All graphical images were prepared with Pymol (PyMOL Molecular Graphics System). X-ray diffraction data was collected at SER CAT ID-22 or BM-22 beamlines of the Advanced Photon Source (Argonne, Ill.), under General User Proposal 44127 (G.O.).

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1.-19. (canceled)
 20. A recombinant antibody or fragment thereof comprising: a heavy chain variable region comprising a heavy chain complementarity determining region (HCDR)1, a HCDR2, and a HCDR3 comprising amino acids at positions 26-33, 51-60 and 99-121 of SEQ ID NO: 230, SEQ ID NO: 240 or SEQ ID NO: 241, respectively and wherein the amino acid sequence of the heavy chain variable region outside of HCDR1, HCDR2, and HCDR3 has an overall sequence identity of at least 90% to SEQ ID NO: 230, SEQ ID NO: 240, or SEQ ID NO: 241; and a light chain variable region comprising a light chain complementarity determining region (LCDR)1, a LCDR2, and a LCDR3, comprising amino acids at positions 27-32, 50-52 and 89-99 of SEQ ID NO: 253, SEQ ID NO: 255 or SEQ ID NO: 261 respectively, and wherein the amino acid sequence of the light chain variable region outside of LCDR1, LCDR2, and LCDR3 has an overall sequence identity of at least 90% to SEQ ID NO: 253, SEQ ID NO: 255, or SEQ ID NO: 261, and wherein the antibody or fragment thereof binds gp41 MPER of HIV-1 envelope.
 21. A recombinant antibody or fragment thereof comprising: a heavy chain variable region comprising heavy chain complementarity determining regions (HCDRs) that have an overall HCDR sequence identity of at least 90% to HCDR amino acids at positions 26-33, 51-60 and 99-121 of SEQ ID NO: 230, SEQ ID NO:240, or SEQ ID NO:241 and wherein the amino acid sequence of the heavy chain variable region outside of HCDR1, HCDR2, and HCDR3 has an overall sequence identity of at least 90% to SEQ ID NO: 230, SEQ ID NO: 240, or SEQ ID NO: 241; and a light chain variable region comprising light chain complementarity determining regions (LCDRs) that have an overall LCDR sequence identity of at least 90% to LCDR amino acids at positions 27-32, 50-52 and 89-99 of SEQ ID NO: 253, SEQ ID NO: 255 or SEQ ID NO: 261 and wherein the amino acid sequence of the light chain variable region outside of LCDR1, LCDR2, and LCDR3 has an overall sequence identity of at least 90% to SEQ ID NO: 253, SEQ ID NO: 255, or SEQ ID NO: 261, and wherein the antibody or fragment thereof binds gp41 MPER of HIV-1 envelope.
 22. A recombinant antibody or fragment thereof comprising: a heavy chain variable region comprising a heavy chain complementarity determining region (HCDR)1, a HCDR2, and a HCDR3 comprising amino acids at positions 26-33, 51-60 and 99-121 of SEQ ID NO: 230, SEQ ID NO: 240 or SEQ ID NO: 241, respectively and wherein the V gene usage of the heavy chain variable region is VH3; and a light chain variable region comprising a light chain complementarity determining region (LCDR)1, a LCDR2, and a LCDR3, comprising amino acids at positions 27-32, 50-52 and 89-99 of SEQ ID NO: 253, SEQ ID NO: 255 or SEQ ID NO: 261 respectively, and wherein the V gene usage of the light chain variable region is a kappa light chain, and wherein the antibody or fragment thereof binds gp41 MPER of HIV-1 envelope.
 23. A recombinant antibody or fragment thereof comprising: a heavy chain variable region comprising heavy chain complementarity determining regions (HCDRs) that have an overall HCDR sequence identity of at least 90% to HCDR amino acids at positions 26-33, 51-60 and 99-121 of SEQ ID NO: 230, SEQ ID NO:240, or SEQ ID NO:241 and wherein the V gene usage of the heavy chain variable region is VH3; and a light chain variable region comprising light chain complementarity determining regions (LCDRs) that have an overall LCDR sequence identity of at least 90% to LCDR amino acids at positions 27-32, 50-52 and 89-99 of SEQ ID NO: 253, SEQ ID NO: 255 or SEQ ID NO: 261, and wherein the V gene usage of the light chain variable region is a kappa light chain, and wherein the antibody or fragment thereof binds gp41 MPER of HIV-1 envelope.
 24. The recombinant antibody or fragment thereof of claim 22 or 23, wherein the V gene usage of the heavy chain variable region is VH3-15.
 25. The recombinant antibody or fragment thereof of claim 22 or 23, wherein the V gene usage of the light chain variable region is kappa light chain 1-39.
 26. The recombinant antibody or fragment thereof of claim 22 or 23, wherein the V gene usage of the heavy chain variable region is VH3-15 and the V gene usage of the light chain variable region is kappa light chain 1-39.
 27. The recombinant antibody or fragment thereof of claim 24, wherein the J gene usage of the heavy chain variable region is JH6.
 28. The recombinant antibody or fragment thereof of claim 24, wherein the J gene usage of the light chain variable region is JK2.
 29. The recombinant antibody or fragment thereof of claim 20 or 22, comprising: a heavy chain variable region comprising a HCDR1, a HCDR2, and a HCDR3 comprising amino acids at positions 26-33, 51-60 and 99-121 of SEQ ID NO: 230 and a LCDR1, a LCDR2, and a LCDR3, comprising amino acids at positions 27-32, 50-52 and 89-99 of SEQ ID NO:
 253. 30. The recombinant antibody or fragment thereof of claim 20 or 22, comprising: a heavy chain variable region comprising a HCDR1, a HCDR2, and a HCDR3 comprising amino acids at positions 26-33, 51-60 and 99-121 of SEQ ID NO: 230 and a LCDR1, a LCDR2, and a LCDR3, comprising amino acids at positions 27-32, 50-52 and 89-99 of SEQ ID NO:
 255. 31. The recombinant antibody or fragment thereof of claim 20 or 22, comprising: a heavy chain variable region comprising a HCDR1, a HCDR2, and a HCDR3 comprising amino acids at positions 26-33, 51-60 and 99-121 of SEQ ID NO: 240 and a LCDR1, a LCDR2, and a LCDR3, comprising amino acids at positions 27-32, 50-52 and 89-99 of SEQ ID NO:
 261. 32. The recombinant antibody or fragment thereof of claim 20 or 22, comprising: a heavy chain variable region comprising a HCDR1, a HCDR2, and a HCDR3 comprising amino acids at positions 26-33, 51-60 and 99-121 of SEQ ID NO: 241 and a LCDR1, a LCDR2, and a LCDR3, comprising amino acids at positions 27-32, 50-52 and 89-99 of SEQ ID NO:
 261. 33. The recombinant antibody or fragment thereof of claim 21 or 23, comprising: a heavy chain variable region comprising heavy chain complementarity determining regions (HCDRs) that have an overall HCDR sequence identity of at least 90% to HCDR amino acids at positions 26-33, 51-60 and 99-121 of SEQ ID NO: 230; and a light chain variable region comprising light chain complementarity determining regions (LCDRs) that have an overall LCDR sequence identity of at least 90% to LCDR amino acids at positions 27-32, 50-52 and 89-99 of SEQ ID NO:
 253. 34. The recombinant antibody or fragment thereof of claim 21 or 23, comprising: a heavy chain variable region comprising heavy chain complementarity determining regions (HCDRs) that have an overall HCDR sequence identity of at least 90% to HCDR amino acids at positions 26-33, 51-60 and 99-121 of SEQ ID NO: 230; and a light chain variable region comprising light chain complementarity determining regions (LCDRs) that have an overall LCDR sequence identity of at least 90% to LCDR amino acids at positions 27-32, 50-52 and 89-99 of SEQ ID NO:
 255. 35. The recombinant antibody or fragment thereof of claim 21 or 23, comprising: a heavy chain variable region comprising heavy chain complementarity determining regions (HCDRs) that have an overall HCDR sequence identity of at least 90% to HCDR amino acids at positions 26-33, 51-60 and 99-121 of SEQ ID NO: 240; and a light chain variable region comprising light chain complementarity determining regions (LCDRs) that have an overall LCDR sequence identity of at least 90% to LCDR amino acids at positions 27-32, 50-52 and 89-99 of SEQ ID NO:
 261. 36. The recombinant antibody or fragment thereof of claim 21 or 23, comprising: a heavy chain variable region comprising heavy chain complementarity determining regions (HCDRs) that have an overall HCDR sequence identity of at least 90% to HCDR amino acids at positions 26-33, 51-60 and 99-121 of SEQ ID NO: 241; and a light chain variable region comprising light chain complementarity determining regions (LCDRs) that have an overall LCDR sequence identity of at least 90% to LCDR amino acids at positions 27-32, 50-52 and 89-99 of SEQ ID NO:
 261. 37. A bispecific antibody comprising the recombinant antibody or fragment thereof of any one of claims 20-23.
 38. The recombinant antibody or fragment thereof of any one of claims 20-23 wherein the antibody or fragment thereof comprises an Fc portion that is modified compared to a naturally occurring Fc domain.
 39. A pharmaceutical composition comprising any one of the antibodies or fragments thereof of any one of claims 20-23, or any combination thereof.
 40. The pharmaceutical composition of claim 39, further comprising another HIV 1 neutralizing antibody.
 41. A pharmaceutical composition comprising a vector, the vector comprising a nucleic acid encoding an antibody or fragment thereof comprising a heavy chain variable region comprising a heavy chain variable region comprising a heavy chain complementarity determining region (HCDR)1, a HCDR2, and a HCDR3 comprising amino acids at positions 26-33, 51-60 and 99-121 of SEQ ID NO: 230, SEQ ID NO: 240 or SEQ ID NO: 241, respectively; and a light chain variable region comprising a light chain complementarity determining region (LCDR)1, a LCDR2, and a LCDR3, comprising amino acids at positions 27-32, 50-52 and 89-99 of SEQ ID NO: 253, SEQ ID NO: 255 or SEQ ID NO: 261 respectively, wherein the antibody or fragment thereof binds gp41 MPER of HIV-1 envelope.
 42. The pharmaceutical composition of claim 41, wherein the vector is suitable for gene delivery and expression.
 43. A pharmaceutical composition comprising a vector, the vector comprising a nucleic acid encoding an antibody or fragment thereof of any one of claims 20-23.
 44. The pharmaceutical composition of claim 43, wherein the vector is suitable for gene delivery and expression.
 45. A method to inhibit HIV-1 infection in a subject comprising administering to the subject the pharmaceutical composition of claim 39 in an effective amount.
 46. The method of claim 45, wherein the pharmaceutical composition is administered in an effective regimen.
 47. The method of claim 45 further comprising administering an additional HIV 1 neutralizing antibody. 